HomeMy WebLinkAbout1992-09-01; City Council; 11875; Status Report on Habitat Management PlanCITQOF CARLSBAD — AGENt£)BILL
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STATUS REPORT ON HABITAT
MANAGEMENT PLAN
CITY MGlOS^-
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RECOMMENDED ACTION:
That the City Council:
(1) accept the Biological Resources and Habitat Analysis Report prepared by the biological
consulting team;
(2) authorize the City Manager to execute supplements to the existing agreements with Consultants
Collaborative Inc. and A. D. Hinshaw Associates to provide for Phase III consultant services; and
(3) direct staff to proceed with Phase III of the Work Program for the Habitat Management Plan.
ITEM EXPLANATION
Background
State and federal wildlife agencies, conservation groups, local government, and the development
industry are in agreement that the reactive, species-by-species and project-by-project approach
used in the past to address wildlife habitat is not the most effective way to protect rare plants and
animals from the threat of extinction, nor is it an efficient way to plan for development. All sides
are now endorsing a proactive approach such as represented by Carlsbad's Habitat Management
Plan (HMP). The proposed listing of the California Gnatcatcher has brought the issue to the
forefront of land use planning in this region.
If the California Gnatcatcher is listed as threatened or endangered, already approved projects
within the Gnatcatcher's habitat could be stopped unless a federal and/or state permit is approved.
The permit process can take up to a year or more for each project that applies. Moreover,
project-by-project habitat planning often results in isolated fragments of habitat that are of
questionable long-term value. A more logical and efficient approach is to pursue a Citywide
permit that would specify in advance which lands must be preserved and which lands can be
developed. If successful, such an effort would resolve all future endangered species issues for
the City. This is what the HMP is intended to accomplish.
Current Status
Beginning in November 1990, the City Council authorized a Work Program consisting of four
phases, as follows:
Phase I - Advisory Group Formation and Startup
Phase II - Biological Inventory and Analysis
Phase III - Plan Development
Phase IV - Plan Implementation
Page Two of Agenda Bill No. \\fK1'5*
Phase II is now completed. Exhibit 1 is the draft Biological Resources and Habitat Analysis
Report, prepared by the biological consulting team and reviewed by the advisory group. The
report includes a comprehensive inventory of all the remaining wildlife habitat in Carlsbad and
shows the documented locations of sensitive species of plants and animals. Based on this
inventory, a rating system was used to show the relative habitat value of specified areas. The
result is a generalized indication of the areas of highest biological value and the designation of
Preserve Planning Areas. Two scenarios were analyzed; one assumes the current status of the
California Gnatcatcher as a candidate for listing as an endangered species while the other scenario
analyzes the situation after listing.
Area 1 Buena Vista Lagoon and Buena Vista Creek
Area 2 Portions of Zones 7, 14, 15 and 16
Area 3 Agua Hedionda Lagoon and adjacent lands
Area 4 Portions of Zones 20 and 21
Area 5 Zones 10 and 18
Area 6 Batiquitos Lagoon
Area 7 A portion of property owned by the Fieldstone Company in Zone 11, which is
already covered by a proposed conservation agreement
Area 8 A portion of Zone 12 (in post-listing scenario only)
The report notes that approximately 2,500 acres of habitat are already protected in Carlsbad. This
includes the three lagoons and the Fieldstone preserve land in Area 7. Not all of the remaining
Preserve Planning Areas will be preserved for habitat purposes. The report recommends that two
or three additional areas of appropriate size be preserved, with suitable linkages to develop a
complete, integrated preserve system.
In the development of the plan thus far, staff and the consultants have been sensitive to private
property rights and the concerns of land owners. Specific parcels have not been targeted for
acquisition, and ongoing projects have not been affected by the plan even though sensitive habitat
is shown to be present. It is important for all parties to understand that the plan at its present
stage is not a regulatory document. It does not prohibit development of any land. It does not
supplant the normal environmental review process, and it does not require additional mitigation.
It does not change the General Plan designation or zoning of any land, and it specifically does not
designate any land as Open Space. It does not require any property owner to give or sell any land
to the City. It is not a local endangered species act, and it does not supplant the existing federal
and state processes for designating endangered species.
The City will benefit from completion of this work in several ways. The City has already
benefitted by having the vegetation inventory prepared, which will be very useful in the update
of the General Plan and accompanying Master EIR. By proactively addressing the issue of
protecting sensitive species, the plan minimizes the economic impacts on the City of future listings
of species as threatened or endangered. It will allow municipal projects, such as roads and parks,
Page Three of Agenda Bill No. // $ 75
to be more sensitively designed to avoid impacting habitat areas and to more readily provide
appropriate mitigation for unavoidable impacts. The process used to arrive at the present
plan has forged a stronger cooperative relationship with both the federal and state wildlife
agencies, which will have long term benefit to the City. Implementation of a preserve and
corridor system will provide additional open space within Carlsbad, benefitting the
environment and Carlsbad residents. A less tangible benefit is the positive recognition that
Carlsbad will receive for having undertaken this unprecedented effort.
Before the City can determine specifically where and how additional wildlife habitat should
be preserved, it will be necessary to complete Phase III of the Work Program. Phase III
involves the actual preparation of a Habitat Management Plan. This phase deals with
identifying the specific areas to be preserved based on the general analysis completed in
Phase II. This phase also deals with the questions of how to acquire the land and how it
will be maintained and managed in perpetuity for its biological value. The tasks to be
carried out are listed in Exhibit^ which is a revised Work Program for Phases HI and IV.
The Work Program for these phases has been revised and updated to reflect tasks
accomplished in Phase II. It is anticipated that Phase III will be completed by Spring 1993.
The firm of Consultants Collaborative Inc. has served as facilitator for Phases I and II. A.
D. Hinshaw Associates has served as environmental consultant. Staff believes that the most
expeditious way to provide the necessary consultant services for Phase III is to supplement
the existing agreement with Consultants Collaborative and A. D. Hinshaw, who will
subcontract for needed biological, financial, and other technical expertise. It is
recommended that the City Council authorize the City Manager to execute supplements to
the existing agreements with Consultants Collaborative and A. D. Hinshaw in a combined
amount not to exceed $150,000 to provide necessary consulting services for Phase III.
FISCAL IMPACT
Funding for the completion of Phase III of the HMP was approved as part of the Planning
Department's budget for FY 1992-93. However, as part of the conceptual mitigation
agreement with the Fieldstone Company regarding its land in the vicinity of Rancho Santa
Fe Road, Fieldstone has agreed to reimburse the City for these costs up to a maximum of
$150,000 upon formal acceptance of a final mitigation agreement.
ENVIRONMENTAL REVIEW
The Habitat Management Plan is a planning study only, and no environmental review is
required. If the plan results in a federal or state permit, environmental documentation will
be required at that time.
Page Four of Agenda Bill No. ///
EXHIBITS
1. Biological Resources and Habitat Analysis Report CM fd-z in fi-y Clerk.* °
2. Revised Phase III and IV Work Program
TABLE OF CONTENTS
Section Page
OVERVIEW 1
1 SAN DIEGO COUNTY, CALIFORNIA: THE REGIONAL SETTING 2
1.1 Introduction \ 2i
1.2 Existing Conditions ^ 2
1.2.1 Regional Overview ^ 2
1.2.2 Topography '. 2
1.2.3 Climate 3
1.2.4 Geology and Soils . .. . r 3
1.2.5 Plant Communities 4
1.2.6 Sensitive Biota 7
1.3 Summary and Conclusions 9
2 CITY OF CARLSBAD: THE LOCAL SETTING 10
2.1 Introduction 10
2.2 Existing Conditions 10
2.2.1 General Topography and Landscape Features 10
2.2.2 Climate 11
2.2.3 Geology and Soils . 11
2.2.4 Plant Communities 11
2.2.5 Sensitive Biota 16
3 RESOURCE INVENTORY AND MAPPING 32
3.1 Introduction 32
3.2 Materials 32
3.3 Methods 32
3.4 Results 33
3.4.1 Vegetation Map 33
3.4.2 Sensitive Species Map 35
TABLE OF CONTENTS (Continued)
Page
4 BIOLOGICAL PRESERVE PLANNING AREA AND DESIGN APPROACH 36
4.1 Introduction 36
4.2 Preserve Design Literature Review 36
4.2.1 Size 36
4.2.2 Shape 37
4.2.3 Isolation/Wildlife Corridors 37
4.2.4 Buffers and Distance Setbacks 37
4.2.5 Other Considerations 40
4.3 Preserve Design Rationale and Approach 40
4.4 Preserve Design Methodology 41
4.4.1 Focused Planning Areas 41
4.4.2 Preserve Feature Definitions and Ratings — Habitat Value 42
4.4.3 Preserve Feature Definitions and Ratings - Habitat Sensitivity 45
4.5 Results - Habitat Value 47
4.5.1 Amount of Natural Habitat 48
4.5.2 Habitat Diversity 48
4.5.3 Habitat Connectivity 49
4.5.4 Adjacent Land Use 49
4.5.5 Composite Habitat Value 49
4.6 Discussion - Habitat Value 50
4.7 Results - Habitat Sensitivity 50
4.7.1 Amount of Sensitive Habitat 51
4.7.2 Sensitive Habitat Diversity 51
4.7.3 California Gnatcatcher 51
4.7.4 Sensitive Plants 52
4.7.5 Sensitive Wildlife 52
4.7.6 Composite Habitat Sensitivity 52
4.8 Habitat Sensitivity — Discussion 53
4.9 Total Habitat Value/Sensitivity - Results 53
4.10 Total Habitat Value/Sensitivity -- Discussion 54
4.11 Limitations of Approach 55
in
TABLE OF CONTENTS (Continued)
Page
5 PRESERVE RECOMMENDATIONS 56
5.1 Introduction 56
5.1.1 Size of Preserve System 56
5.2 Potential Core Preserve Areas 56
5;2.1 Methods 57
5.2.2 Results 57
53 Potential Wildlife Corridors 69
5.3.1 Methods 69
5.3.2 Results 70
5.4 Conceptual Preserve System 72
5.5 Compatible Land Use Analysis 73
5.6 Conclusion 74
6 ACKNOWLEDGEMENTS 75
7 LITERATURE CITED 76
Appendices
A. Federal and State Designated Sensitive Plant and Wildlife Species Resident or
Breeding in San Diego County
B. Environmental Impact Reports and Other Documents Consulted
IV
TABLE OF CONTENTS (Continued)
LIST OF TABLES
1. Comparison of Pre-European and 1988 Vegetation Coverage for San Diego
County 5
2. Classification System for Habitat Communities Occurring in the City of Carlsbad 12
3. Acreages by Aggregated Vegetation Types within the Carlsbad Habitat Management
Plan Study Area 34
4. Frequency Distribution for Habitat Value Features 48
5. Composite Habitat Value 50
6. Frequency Distribution for Habitat Sensitivity Features 51
7. Composite Habitat Sensitivity 53
8. Total Habitat Value/Sensitivity Frequency Distribution 54
9. Acreages by Aggregated Vegetation Types for the Pre-California Gnatcatcher
Listing Preserve Planning Areas 58
10. Acreages by Aggregated Vegetation Types for the Post-California Gnatcatcher
Listing Preserve Planning Areas 60
11. Pre-California Gnatcatcher Listing Preserve Planning Area Sensitive Species
Records 63
12. Post-California Gnatcatcher Listing Preserve Planning Area Sensitive
Species Records 64
LIST OF FIGURES
Follows
Page
1. Regional Map 2
2. Vicinity Map 10
3. Vegetation Map 33
4. Sensitive Species Map (Sheets 1 & 2) 35
5. Pre-Gnatcatcher Listing Focused Planning Areas 41
6. Post-Gnatcatcher Listing Focused Planning Areas 41
7. Habitat Value Map 49
8. Habitat Sensitivity Map 52
9. Total Habitat Value/Sensitivity Map 53
10. Pre-Listing Proposed Preserve Planning Areas/Corridors 57
11. Post-Listing Proposed Preserve Planning Areas/Corridors 57
OVERVIEW
THE CARLSBAD HABITAT MANAGEMENT PLAN
At the direction of the Carlsbad City Council, the Community Development Department has
undertaken preparation of a Habitat Management Plan (HMP) for the City. The goals of the project
are to develop an HMP that will: (1) constitute a major component of the Conservation Element
of the General Plan; and (2) result in implementation of a plan that will proactively address
protection of sensitive plant and animal species and their habitats as development occurs in Carlsbad.
The HMP will provide direction about how best to identify, conserve, use, and manage the City's
biological habitat resources and should result in an effective habitat preserve system. Decisions
regarding the design of the preserve system will be based on scientific theory and be consistent with
current knowledge from the field of conservation biology.
A broadly based Citizens Advisory Group that contains representatives of land owners, environmental
groups, state and federal regulatory agencies, and City operating departments provides input and
oversight to the project.
SECI ON
SAN DIEGO COUNTY, CALIFORNIA:
The Regional Setting
BIOLOGICAL RESOURCES AND HABITAT ANALYSIS
in support of the QlT OF CARLSBAD HABITAT MANAGEMENT PLAN
SECTION 1
SAN DIEGO COUNTY, CALIFORNIA
THE REGIONAL SETTING
1.1 INTRODUCTION
This section provides an overview of the regional setting in which the HMP is being developed.
Other jurisdictions within San Diego County are currently undertaking or considering similar natural
resources planning programs. While Carlsbad's plan is intended only to address land and habitats
within its corporate limits, it is important in formulating such a plan to be aware of regional issues
and other programs. As such, the Carlsbad HMP is intended to be consistent with three known
subregional programs - the San Diego Clean Water Program Multi-Species Conservation Program
(MSCP), the County of San Diego Open Space and Habitat Management Plan (OSHMP), and the
North County Multiple Habitat Conservation Program (MHCP), as well as the anticipated Central
County Wildlife Forum Plan. The plan also is intended to be consistent with the pilot Natural
Communities Conservation Planning (NCCP) for coastal sage scrub habitat in Southern California.
This state program, if successful, would provide regional resource planning and protection for coastal
sage scrub and its threatened plant and wildlife species.
1.2 EXISTING CONDITIONS
1.2.1 REGIONAL OVERVIEW
San Diego County, California, is the most southwesterly county in the continental United States. It
is bordered on the east by Imperial County, on the north by Riverside and Orange counties, on the
west by the Pacific Ocean, and on the south by Baja California, Mexico (Figure 1). Roughly
trapezoidal in shape, it extends about 70 miles (110 km) from east to west and 60 miles (80 km) from
north to south; it covers approximately 4,250 square miles (7,000 square km). Elevations range from
sea level along the coast to 6,533 feet (2,000 m) at the highest point — Hot Springs Mountain near
Warner Springs.
San Diego County supports an exceptionally diverse biota (i.e., the animal and plant species of a
region): over 1,500 species of plants (Beauchamp 1986), 160 breeding and about 275 non-breeding
species of birds (McCaskie 1977), 75 species of reptiles and amphibians (Lichtwardt and Gold 1980),
125 resident species of butterflies (Brown 1991), 80 species of mammals (Bond 1977), and an
estimated 10,000 to 20,000 species of terrestrial and aquatic invertebrates. A number of factors
combine to support this rich biodiversity, including varied topography, complex climatic conditions,
a wide variety of soil types, and a unique biogeographic history.
San Diego County is also one of most rapidly-growing areas of the country. Because the greatest
human population expansion and habitat change are occurring primarily along the coast where the
most sensitive biological resources occur, the conflicts of growth and maintenance of biological
diversity are acute. Planning has not previously been done on a regional scale for this area resulting
in a highly fragmented natural landscape. This, in turn, makes preserve design more difficult and
necessitates designation or creation of wildlife corridors to interconnect habitat fragments.
1.2.2 TOPOGRAPHY
Physical features found along the western edge of the county include sandy beaches, wide river
floodplains, low-lying salt marshes, and rocky bluffs. These areas support coastal dune, coastal salt
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Carlsbad Habitat Management Plan
Regional Map
marsh, Torrey pine woodland, and maritime succulent scrub plant communities. Inland from the coast
a series of coastal mesas, foothills, and canyons support coastal sage scrub, southern mixed chaparral,
chamise chaparral, and oak and riparian woodland communities. Further inland are the foothills of
the Peninsular Range Mountains, covered primarily with chamise chaparral, southern mixed chaparral,
and oak woodlands. Riparian woodlands occur along watercourses. The county is bisected north to
south by an extension of the Peninsular Ranges, including the Palomar, Cuyamaca and Laguna
Mountains, which constitute a formidable barrier between the broad chaparral belt to the west and
the arid lowlands of the Colorado Desert to the east. The mountains reach peak elevations of over
6,000 feet above sea level (1,850 m) before dropping sharply to near sea-level in the Anza-Borrego
Desert. The mountainous areas support chaparral, oak woodland, montane coniferous forest, mixed
evergreen forest, and riparian woodlands. The desert is topographically diverse, extending from the
eastern slopes of the mountains to far beyond the eastern border of the county. This region is
vegetationally diverse as well, supporting chaparral, pinyon-juniper woodland, creosote bush scrub,
alkaline sink, dune, playa, and riparian habitats.
1.2.3 CLIMATE
Based on average temperature and precipitation, San Diego County includes four natural climatic
zones (Pryde 1984): (1) cool Mediterranean, (2) warm Mediterranean, (3) semiarid (or steppe), and
(4) arid (or desert). All of these climatic zones are characterized by cool, moist winters and hot, dry
summers. Within these four types, topographic features and proximity to the ocean combine to
create a diversity of specific micro-climatic regimes within the county. Along the narrow coastal strip,
fog constitutes a major source of water for many native plants. Average precipitation along the coast
ranges between 10 and 12 inches (25-30 cm) per year. Proximity to the ocean helps maintain
relatively constant temperatures. The lowland mesas (also known as marine terraces) are slightly
warmer than the immediate coast and receive slightly more precipitation - 12 to 16 inches (30-40 cm)
per year. Above about 1,300 feet (400 m) elevation, the mountainous areas receive considerably
more precipitation than the coastal and mesa areas to the west, and the vegetation is taller and
denser. Above about 3,900 feet (1,200 m) elevation, temperature and precipitation regimes support
coniferous forests. Winter snow is infrequent but regular in the higher elevations of the mountains.
The rain-shadow effect of the mountains on lands further east, inhibiting moisture-laiden clouds from
reaching further inland, is manifested in dry, desert conditions that prevail throughout most of the
year. Desert temperatures are extremely variable; summer temperatures typically exceed 100 degrees
Fahrenheit (38 degrees Celsius) in the lower valleys.
1.2.4 GEOLOGY AND SOILS
San Diego County is divisible into two large geomorphic provinces on the basis of surface geology
and relief (Pryde 1984). The Coastal Province occupies the western portion of the county,
corresponding to the region of sedimentary surface rocks. The dominant relief of this province is a
series of marine terraces also known as mesas. The Peninsular Range Province comprises the portion
of the county located east of the Coastal Province and is composed of plutonic and metavolcanic
surface rocks. The major relief elements of this province include the general northwest-southeast
trending foothills and mountain ranges, the highest peaks, and the steep eastern slopes of the
mountains.
According to Bowman (1973), 53 different soil series are present in San Diego County, including
sandy, cobbly, loamy, and clayey, and soils associated with gabbro parent material and Santiago Peak
metavolcanic formations. A soil series is a group of closely related soils that shares similar texture
of surface, slope, stoniness, and other characteristics that affect use of the soil by man. On the
coastal terraces most of the soil series are comprised of sandy loams, clay loams, and clays. In the
foothills on the western slopes of the mountains, the soils generally are well-drained sandy loams or
silt loams overlaying decomposed granitic or metavolcanic rock. The mountainous areas are
characterized by well-drained sandy loams over granitic bedrock. In the desert, soils range from
virtually none on the steeper slopes, to coarse sandy alluvial soils on the gentler slopes. Soil diversity
acts to promote botanical diversity: many endemic plant species are confined to a single or a few soil
types (Oberbauer 1991 a).
1.2.5 PLANT COMMUNITIES
A plant community is an association of plant species that is readily recognizable in the field. Plant
communities are thought to reflect particular biogeographic and ecological conditions. Plant
communities are recognized by their "dominant" species, which tend to occur together.
Plant communities are closely related to climatic zones, available moisture, slope aspect (exposure),
soil type, and disturbance. For some communities, such as coastal sage scrub, chaparral, and southern
interior cypress forest, fire plays an integral role in community succession and is necessary to maintain
the integrity and productivity of the habitat (Zedler 1977). For other communities, perturbations may
have very long-lasting dramatic effects. Plant communities are the major determinants of wildlife
diversity and abundance, and they play a vital role in determining species distributions. The major
plant communities present in San Diego County are discussed briefly below (see Table 1).
Terminology in the table is after Oberbauer (1991b) while the terminology in the text follows Holland
(1986).
Plant communities present along the coastal strand include a number of dune communities (i.e., active
coastal dunes, southern foredunes, and southern dune scrub). The plants of these communities
typically are small herbaceous or succulent species, often with a prostrate growth habit. They cover
the surface sparsely, leaving areas of bare sand. The general aspect of this community is determined
by nearly constant onshore breezes, fine sandy soils, and moderately saline conditions. Among the
most common species in this habitat type are sea-rocket (Cakile maritima), beach evening-primrose
(Camissonia cheiranthifolia), beach bur (Ambrosia chamissonis), and sea-fig (Carpobrotus spp.).
Coastal strand vegetation has been replaced in most areas by recreational or urban development, and
elsewhere it has been degraded by frequent human disturbance. Dune communities are best
preserved at Border Field and Silver Strand State Parks. In all other coastal areas throughout the
county, coastal strand or dune communities are extremely limited.
Wetland communities found along the coastal strand include southern coastal salt marsh, coastal
brackish marsh, and coastal and valley freshwater marsh. In these aquatic and semi-aquatic habitats,
plant species composition varies considerably, depending upon duration of inundation, tidal flow or
runoff, and salinity. Salt marshes are characterized by low-growing succulents such as pickleweed
(Salicornia spp.), salty susan (Jaumea camosa), salt grass (Distichlis spicata), salt-cedar
(Monanthochloe littoralis), and other halophytic (salt-tolerant) species. Some salt marsh systems
include an outer marsh characterized by stands of tall cordgrass (Spartina foliosd). Salt marsh
communities are highly productive systems and function as hatcheries for many species of fish, and
provide food and refuge resources for a variety of locally resident and migratory water birds. Salt
marsh habitat is best developed at places like Tijuana Estuarine National Wildlife Refuge, the mouth
of the Sweetwater River, and the mouth of the Santa Margarita River. Freshwater marshes typically
are dominated by cattails (Typha spp.), bulrushes (Scirpus spp.), and dock (Rwnex spp.). Patches of
this habitat are present at the upper ends of Buena Vista, Agua Hedionda, Batiquitos, and San Elijo
lagoons, where a mixture of plants of salt and freshwater habitats is encountered. Smaller freshwater
marshes grow around the perimeter of many lakes and ponds on the coastal slope.
TABLE 1
COMPARISON OF PRE-EUROPEAN AND 1988 VEGETATION COVERAGE
FOR SAN DIEGO COUNTY
(AFTER OBERBAUER 199th1)
Original Ac. Current Ac. Change
Chamise Chaparral2
Creosote Bush Scrub
Mixed Chaparral2
Coastal Sage Scrub2'3
Desert Transition
Native Grassland2
Oak Woodland (sparse)
Coniferous Forest
Riparian Woodland2
Oak Woodland (dense)2
Desert Wash
Coastal Mixed Chaparraf
Mountain Meadow
Juniper Woodland
Pinon Woodland
Coastal Salt Marsh2
Creosote Bush-Wash Complex
Mesquite Bosque
Cypress Woodland
Coastal Strand2
Dry Lake-sink
Freshwater Marsh2
Torrey Pine Woodland
Agriculture-Urban complex4
Disturbed Grassland4
Agriculture4
Lakes/Reservoirs4
Total 2,709,360
Direction
of Change
599,820
532,290
500,540
480,260
143,680
125,680
80,500
79,010
34,580
28,900
21,040
20,620
16,480
12,230
8,190
6,530
5,040
4,610
4,440
1,940
1,580
1,090
310
0
0
0
0
466,947
500,220
467,715
135,370
143,680
7,250
78,540
79,010
13,570
27,140
21,040
2,530
16,480
12,230
8,190
810
5,040
4,209
4,229
0
1,580
100
250
339,030
203,760
159,640
10,800
22%
6%
7%
72%
0%
94%
2%
0%
61%
6%
0%
88%
0%
0%
0%
68%
0%
9%
5%
100%
0%
91%
19%
100%
100%
100%
100%
Reduction
Reduction
Reduction
Reduction
No Change
Reduction
Reduction
No Change
Reduction
Reduction
No Change
Reduction
No Change
No Change
No Change
Reduction
No Change
Reduction
Reduction
Essentially gone
No Change
Reduction
Reduction
New Type
New Type
New Type
New Type
2,709,360
i _
4 _
After: Oberbauer, T.A. 1991. In: Abbott, P. and B. Elliot. Geol. Soc. North Amer., So.
Calif. Reg., Sympos. Oct.-21-24,1991, San Diego, California. Does not follow Holland (1986)
precisely.
Occurs in Carlsbad
Oberbauer splits coastal sage scrub into two components: inland sage scrub and maritime
sage scrub. Inland sage scrub has been reduced from 428,480 acres to 131,000 acres (a 69%
reduction). Maritime sage scrub has been reduced from 51,780 acres to 4,370 acres (a 92%
reduction).
Man made
Terrestrial upland vegetation closest to the coast includes Diegan coastal sage scrub, southern coastal
bluff scrub, maritime succulent scrub, southern maritime chaparral, and Torrey pine forest. Diegan
coastal sage scrub consists primarily of aromatic shrubs and sub-shrubs with an understory of annual
herbs and perennial grasses. Characteristic species include coastal sagebrush (Artemisia California),
California buckwheat (Eriogonum fasciculatuni), white sage (Salvia apiand), lemonadeberry (Rhus
integrifolia), laurel sumac (Malosma laurind), and purple needlegrass (Stipa pulchra). Typical coastal
sage scrub occurs in many places, including the hills around Poway, the Dulzura-Jamul area, south
of Lake Hodges, and portions of Camp Pendleton. Southern coastal bluff and maritime succulent
scrub include a variety of succulents and cacti, such as velvet cactus (Bergerocactus emoryi), fish-hook
cactus (Mammillaria dioica), coast cholla (Opuntia proliferd), San Diego barrel cactus (Ferocactus
viridescens), prickly-pear cactus (Opuntia littoralis), cliff-spurge (Euphorbia miserd), bladder-pod
(Cleome isomeris), and several species of dudleya (Dudleya spp.), mixed with typical sage scrub
species. This community type is well developed at Torrey Pines State Park, Tijuana Hills above
Border Field State Park, and Cabrillo National Monument. Southern maritime chaparral is limited
to the area between Mount Soledad and southern Carlsbad. It is a community characterized by
several endemic shrubs, usually growing on sandstone: Del Mar Manzanita (Arctostaphylos glandulosa
var. crassifolid), wart-stemmed ceanothus (Ceanothus verrucosus), coast spice bush (Cneoridium
dumosuni), mission manzanita (Xylococcus bicolof), and Del Mar mesa sand-aster (Corethrogyne
filaginifolia var. linifolia). Torrey pine forest is an exceedingly restricted community known only from
the vicinity of Del Mar and Torrey Pines State Reserve in San Diego County. It is an open-to-
moderately dense forest dominated by Torrey pine (Pinus torreyana), with an extremely variable
understory.
Scattered on flat-topped mesas, marine terraces, and some valleys is a unique habitat that is,
unfortunately, one of the most depleted habitat types in San Diego County — vernal pools (San Diego
Mesa hardpan vernal pool and Otay Mesa claypan vernal pool). These small shallow pools develop
in "mima mound" topography where an underlying semi-impermeable hardpan layer intercepts winter
rainfall and creates a perched water table. Vernal pools support a unique and ephemeral aquatic and
semi-aquatic biota, quite distinct from the adjacent chaparral or grassland, that includes several plant
species recognized as rare, threatened, or endangered by local, regional, and national conservation
agencies, including San Diego mesa mint (Pogogyne abramsii), Otay mesa mint (Pogogyne nudiuscula),
San Diego button-celery (Eryngium aristulatum var. parishii), California Orcutt grass (Orcuttia
califomica), and San Diego navarretia (Navarretia fossalis). Vernal pools are found in several areas
of the county, including Otay Mesa, Kearny Mesa, Del Mar Mesa, Clairemont Mesa, San Marcos,
Ramona, and Fletcher Hills (Bauder 1986).
Inland from the coast, chaparral is the dominant plant community, covering about 35 percent of the
county's land surface. Although several types of chaparral are recognized by Holland (1986) (i.e.,
southern mixed chaparral, chamise chaparral, scrub oak chaparral, mixed montane chaparral, mesic
north slope chaparral, and southern north slope chaparral), all are composed of tall shrubs with hard
evergreen leaves and stiff woody stems. Plant species composition varies from region to region within
the county, but dominant species usually include chamise (Adenostoma fasciculatuni), manzanitas
(Arctostaphylos spp. and Xyloccocus bicolof), wild-lilac (Ceanothus spp.), toyon (Heteromeles
arbutifolia), mountain-mahogany (Cercocarpus spp.), Spanish bayonet (Yucca whipplei), and interior
scrub oak (Quercus berberidifolid). Fire plays an integral role in the succession of chaparral
communities, and many of the resident plant species are highly adapted for vigorous vegetative
reproduction (crown- and stump-sprouting) following fires.
Occurring throughout the coastal area and into the foothills and mountains are several types of
natural grasslands that often are associated with clayey soils. Coastal perennial grasslands may range
in size from patches within sage scrub or chaparral that are less than 100 square feet to (rarely) 20
to 100 acres. They often are dominated by purple needlegrass, a number of non-native grasses (i.e.,
Avena spp., Bromus spp., Gastridium ventricosum, Vulpia spp.), sanicles (Sanicula spp.), blue-eyed
grass (Sisyrinchium bellum), and gum-plant (Grindelia robusta).
Riparian woodlands (i.e., southern coast live oak riparian forest, southern arroyo willow riparian
forest, southern cottonwood-willow riparian forest, and southern willow scrub) cover less than 0.5
percent of the county's area. Although small in acreage, these woodlands support the highest
diversity and greatest abundance of wildlife species of any community type; riparian woodlands are
noted for their rich diversity of breeding bird species (Unitt 1984). Riparian habitats play a vital role
in nutrient recycling and in water quality maintenance. Along large, perennial river courses and
smaller, seasonally moist drainages, the woodlands are comprised of willows (Salix spp.), Fremont
cottonwood. (Populus fremontii), and western sycamore (Platanus racemosd), with a tangled understory
of poison-oak (Toxicodendron diversilobum), desert grape (Vitis girdiana), and a variety of other
hydrophytic (wetland) species. Canyon bottoms that do not have enough water to support the full
complement of riparian vegetation often contain sycamores. In drier canyon bottoms, on north-facing
slopes, and along the edges of valleys, dense groves of coast live oak (Quercus agrifolia) form a closed
canopy oak woodland. Another type of oak woodland occurs in some parts of the foothill region,
where widely spaced individuals of the endemic Engelmann oak (Quercus engelmannii) form a sparse
woodland or oak savannah.
Coniferous woodland communities (Jeffrey pine forest, western ponderosa pine forest, and Coulter
pine forest) are restricted to montane habitats and some isolated peaks that receive over about 18
inches (46 cm) of rain per year. Pines (Pinus spp.) are the dominant plants of this community, but
canyon live oak (Quercus chrysolepis), black oak (Quercus kelloggii), and wild-lilac (Ceanothus spp.)
also are important components. The composition and character of this community vary with humidity
and exposure. In drier, flatter areas, the trees are more widely spaced, there is little ground cover,
and Jeffrey (Pinus jejfreyi) and Coulter pines (Pinus coulteri) dominate. In more humid areas, such
as Cuyamaca Mountain, Palomar Mountain, or on steep north-facing slopes, conifers are more
diverse, and the flora includes incense-cedar (Calocedrus decurrens), white fir (Abies concolor), big-
cone Douglas-fir (Pseudotsuga macrocarpd) and sugar pine (Pinus lambertiana).
Scrub vegetation covers most of the desert edge at the steep eastern escarpment of the mountains
between about 2,500 and 4,000 feet (760-1,220 m). This area includes elements of chaparral and
creosote bush scrub (described below), as well as plant species found sparingly in other areas the
county. The most prominent of these are California juniper (Juniperus califomica), turpentine broom
(Thamnosma montana), and desert apricot (Prunus fremontii).
Most of the lower desert area is covered by a sparse scrub community known as Sonoran creosote
bush scrub. Creosote bush (Larrea tridentatd) is the dominant shrub, but the density of plants is
much lower than that found in other vegetational communities. Sub-dominants in this habitat include
ocotillo (Fouqueria splendens), brittlebush (Encelia farinosa), barrel cactus (Ferocactus acanthodes),
and burrobush (Ambrosia dumosa). Other communities found in this drier eastern portion of the
county include active desert dune, Sonoran mixed woody and succulent scrub, desert greasewood
scrub, desert dry wash woodland, and peninsular juniper woodland and scrub. Although dry and
desolate during most of the year, the desert areas usually come to life in the spring following normal
winter rainfall. Wildflower displays may be magnificent during this brief flowering season.
1.2.6 SENSITIVE BIOTA
Southern California has a long history of human use and consequent alteration of the ecosystem, but
it has experienced rapid urban expansion and habitat change over the past three or four decades; San
Diego County has not been immune. Although habitat degradation has occurred throughout much
of the county, the coastal areas have been altered the most severely. As well as providing prime sites
for housing and other development, these areas have been disrupted by the abuses of recreation and
off-road vehicles. According to the City of San Diego (Hix 1990), the native coastal strand
community has been eliminated nearly entirely; coastal salt marsh has been reduced by greater than
87 percent; coastal sage scrub has lost over 70 percent of its previous acreage; vernal pool habitats
have been reduced by 96 percent; and coastal mixed chaparral has declined by more than 87 percent
in San Diego (see Table 1). The net overall result of this considerable loss in native habitat is the
concurrent decrease in native wildlife and plant species. (See Appendix A for lists of wildlife and
plant species in San Diego County with federal and state sensitive species designations.)
Several species of birds associated with disappearing habitat types and/or habitat degradation are
recognized as threatened or endangered by state or federal agencies: California brown pelican
(Pelecanus occidentalism light-footed clapper rail (Rallus longirostris levipes), Belding's Savannah
sparrow (Ammodramus sandwichensis beldingi), and California least tern (Sterna antillarum browni),
all associated with coastal estuaries and salt marsh habitats; and least Bell's vireo (Vireo belliipusillus),
restricted to riparian woodlands. Also receiving much attention is the federal proposed endangered
California gnatcatcher (Polioptila califomicd), occurring primarily in coastal sage scrub communities
below about 1,200 feet (370 m). Other species recognized as sensitive include coastal cactus wren
(Campylorhynchus brunneicapillus sandiegensis), sage sparrow (AimophUa belli), Southern California
rufous-crowned sparrow (AimophUa ruficeps canescens), California horned lark (Eremophila alpestris
actia), and several species of raptors (birds of prey).
Mammal species occurring in San Diego County listed as threatened or endangered by the U.S. Fish
and Wildlife Service (USFWS) or the California Department of Fish and Game (CDFG) include
Stephens' kangaroo rat (Dipodomys Stephens!), found in the northwestern portion of the county and
on Camp Pendleton; and peninsular bighorn sheep (Ovis canadensis cremnobates), an inhabitant of
the rugged hills in the desert portion of the county. The ringtail (Bassariscus astutus), a state fully
protected species, occurs in riparian, scrub, and forest habitats in the county. The CDFG recognizes
20 species of mammals that occur within San Diego County as "Species of Special Concern," including
eight species of bats. Species that are both federal Category 2 candidates and on the state list of
sensitive species include the Pacific pocket mouse (Perognathus longimembris paciftcus), the Los
Angeles pocket mouse (Perognathus longimembris brevinasus), and four bats. In addition, there are
several new federal Category 2 candidates that are not yet designated by the State as sensitive species
(see Appendix A).
Reptiles that are recognized as federal Category 1 or 2 candidates for listing as endangered by the
USFWS or as Species of Special Concern by CDFG include the San Diego horned lizard
(Phymosoma coronation blainvillei), orange-throated whiptail (Cnemidophorus hyperythrus beldingi),
northern red-diamond rattlesnake (Crotalus ruber), coastal whiptail (Cnemidophorus tigris
multiscutatus), barefoot banded gecko (Coleonyx switald), and San Diego mountain kingsnake
(Lampropeltis zonata pulchra). Sensitive or declining amphibians include western spade-foot toad
(Scaphiopus hammondi), reg-legged frog (Rana aurora draytoni), and arroyo toad (Bufo
[microscaphus califomicus] califomicus).
Seven species of butterflies indigenous to San Diego County are recognized as federal Category 2
candidates for listing as threatened and endangered, namely the Laguna Mountains skipper (Pyrgus
ruralis lagunae), wandering skipper (Pseudocopaeodes eunus), Harbison's dun skipper (Euphyes vestris
harbisoni), salt marsh skipper (Panoquina errans), Hermes copper (Lycaena hermes), Thome's
hairstreak (Mitoura thomef), and quino checkerspot (Euphydryas editha quind). The USFWS has
been petitioned to list several of these species as endangered. Also, the globose dune beetle (Coelus
globosus), a resident of coastal dunes, is a federal Category 2 candidate species, and two other
invertebrates — the Riverside fairy shrimp (Streptocephalus woottonii) and San Diego fairy shrimp
(Branchinecta sandiegoensis) have been proposed or petitioned to be listed as endangered.
8
San Diego County exhibits an exceptionally high degree of floral endemism - it contains numerous
plant species that are found nowhere else. With 173 species recognized as sensitive by the California
Native Plant Society (Smith and Berg 1988), San Diego County is second only to San Bernardino
County in this regard. Plant species of San Diego County listed as threatened or endangered by the
USFWS include salt marsh bird's-beak (Cordylanthus maritimus), restricted to coastal salt marshes,
and San Diego mesa mint (Pogogyne abramsii), an inhabitant of San Diego Mesa hardpan vernal
pools. State-listed rare, threatened, or endangered plant species include the two listed above, plus
San Diego thornmint (Acanthomintha Uicifolia), coastal dunes milk vetch (Astragalus tener var. titi),
Encinitas baccharis (Baccharis vanessae), Dunn's mariposa lily (Calochortus dunni), San Diego button-
celery (Eryngium aristulatum var. parishii), and many others. The USFWS recognizes 76 species of
local plants as federal Category 1 or 2 candidates, and they have proposed three species for listing
as endangered: Otay mesa mint, San Diego button-celery and California Orcutt grass.
San Diego County also supports a variety of sensitive habitats. A sensitive habitat is defined as a
vegetation community type that has been significantly depleted due to development and has been
identified as warranting protection by the CDFG (e.g., coastal sage scrub, coastal strand, or coastal
salt marsh), uncommon within a region, but common elsewhere (e.g., Jeffrey pine forest is limited in
San Diego County), as habitat that supports rare, endangered, or threatened plant or animal species,
or areas that are needed to maintain a balanced ecosystem or wildlife corridor (City of San Diego
1991). Sensitive habitats in San Diego County relevant to the City of Carlsbad and this document
are coastal sage scrub (including all subassociations), southern maritime chaparral, oak woodland,
riparian scrub, freshwater marsh, salt marsh, open water, and native grassland.
1.3 SUMMARY AND CONCLUSIONS
Because of its highly varied topography, soils, and climatic conditions, San Diego County supports an
exceedingly diverse biota. Numerous plant communities are present within the county boundaries,
each of which supports its own distinctive assemblage of plant and wildlife species.
Urban growth throughout San Diego County has had a tremendous effect on the local biota. Many
plant and animal species have become increasingly rare throughout the region and some have become
locally extinct. Projected land development and human population growth in the region will increase
the pressure on a large number of habitats and species that are literally now on the brink of
extinction. Although sensitive species are designated as threatened, endangered, rare, declining, or
depleted by local or regional conservation agencies, sensitive habitats are not provided with such
designations. The most depleted habitat types include coastal dunes, coastal salt marsh, maritime
succulent scrub, coastal sage scrub, native grassland, riparian woodland, and vernal pool. The loss
of natural habitat results in the decline of native plant and wildlife species.
San Diego County is one of the most desirable places in the country to live. In order for the region
to continue to offer a high quality of human life, severe challenges in natural resource management
must be met, including preservation of open space, maintenance of water and air quality, traffic
management, control of noise pollution, and preservation of our natural heritage. Concurrently, the
economic vitality of the region must be maintained and enhanced for the present and the future.
To achieve these objectives, it is vital to design and implement development alternatives that are
compatible with the preservation of biological resources. Habitat management plans, such as that
under development by Carlsbad, and similar plans being undertaken by government and individuals,
provide a means for attaining this goal.
SECT ON 1
CITY OF CARLSBAD:
The Local Setting
BIOLOGICAL RESOURCES AND HABITAT ANALYSIS
in support of the CITY OF CARLSBAD HABITAT MANAGEMENT PLAN
SECTION 2
CITY OF CARLSBAD
THE LOCAL SETTING
2.1 INTRODUCTION
The City of Carlsbad is situated along the Pacific coast of California, in northwestern San Diego
County, approximately 30 miles (45 km) north of the City of San Diego. It is bordered on the north
by the City of Oceanside, on the northeast by the City of Vista, on the east by the City of San
Marcos, on the south by the City of Encinitas, and on the west by the Pacific Ocean (Figure 2). It
extends about 4.5 miles (6 km) from east to west and about 7.0 miles (9 km) from north to south; it
covers approximately 40 square miles (about 24,000 acres or 15.44 square Km). Elevations range
from sea level along the coast to about 960 feet (280 m) at the highest point at the southeastern
border of the City.
The City of Carlsbad has been a valuable agricultural area since prior to the 20th century, and has
experienced significant urban expansion over the past three or four decades. The human population
of the City is estimated to be approximately 63,000. Urban development for housing and other uses
has resulted in degradation and outright loss of significant blocks of native habitat. Encampments
of migrant workers and homeless people also have degraded much habitat, particularly in riparian
areas. Native communities associated with the coastal areas have been disrupted by the abuses of
active recreation and off-road vehicles.
Although much of the City has been subject to agriculture, housing, commercial development and
other uses, open space areas within Carlsbad support a diverse biota and a variety of sensitive plant
and wildlife species. Over 300 species of plants, 200 species of birds, 25 species of reptiles and
amphibians, 20 species of mammals, 44 species of fish, 45 species of butterflies, and several thousand
species of terrestrial and aquatic invertebrates retain populations within the City. Information on the
status of many of these populations, however, is lacking, and it is not known whether the remaining
populations of these species are viable.
As with much of San Diego County, the City of Carlsbad has experienced significant urban growth
in recent years. The entire City lies within 4.5 miles of the coast; hence human population expansion
and habitat change is concentrated within the coastal area where many sensitive and rapidly
diminishing biological resources occur. Consequently, conflicts between urban growth and the
maintenance of biological diversity are encountered frequently. These factors make conservation
planning in these areas particularly challenging.
2.2 EXISTING CONDITIONS
2.2.1 GENERAL TOPOGRAPHY AND LANDSCAPE FEATURES
The western edge of the City, lying along the Pacific coast, is characterized by sandy beaches and
three low-lying river estuaries or lagoons ~ Batiquitos Lagoon, Agua Hedionda Lagoon, and Buena
Vista Lagoon. Buena Vista Lagoon, at the northern border of the City, is fed by Buena Vista Creek,
a local drainage that forms much of the border between the cities of Oceanside and Carlsbad. The
watershed of Agua Hedionda Lagoon includes a drainage that extends from Lake Calavera in the
northeastern corner of Carlsbad. Batiquitos Lagoon lies along the southern boundary of the City and
extends inland from the coast to near El Camino Real, where it receives runoff from slopes on the
north side of the lagoon and a drainage from the south. The lagoons dominate the coastal landscape
10
Oceans/da
o
TV
o
o
City of Carlsbad
\
n
Vista
San
Marcos
OUtCNHAJN Rflt
Olivenhain
Encinitas
BlVD
1" = 6500'
Carlsbad Habitat Management Plan
Vicinity Map
of Carlsbad and provide habitat for a variety of resident and migratory bird species. With the
exception of some habitat that immediately borders the estuaries, native communities on the
immediate coast either have been degraded severely by human activities or have been lost altogether
to development. Inland from the coast is a series of low coastal mesas and rolling foothills,
supporting shrublands, grasslands, and agriculture, with intervening ravines and canyons supporting
narrow oak woodland, riparian scrub, coastal sage scrub, and chaparral communities. Two large
freshwater bodies occur within Carlsbad near the eastern edge of the City — Lake Calavera and
Squires Dam. Both support adjacent freshwater marsh and riparian woodlands. A deep, roughly east-
west trending gorge dominates the landscape locally in the southeastern portion of the City through
the Fieldstone Company-owned lands east of La Costa.
Agriculture (including tomatoes, flowers, and others) is a dominant feature of the landscape,
particularly in the area north of Palomar Airport Road east of Paseo del Norte, and south of Palomar
Airport Road east of El Camino Real. Private golf courses also occupy considerable areas of open
space, including courses associated with the La Costa and Aviara developments. Golf courses
typically occupy lower, more level bottomland areas between steep or sloping terrain.
2.2.2 CLIMATE
Based on average temperature and precipitation, the City of Carlsbad lies entirely within the semiarid
(or steppe) climatic zone (Pryde 1984). Average annual precipitation is 10.7 inches. Average annual
temperature is 59.2 degrees Fahrenheit (F); average July/August high temperature is 72.9 degrees F;
and average January low temperature is 42.6 degrees F. Temperatures typically exhibit greater
differences furthest from the coast. Highly seasonal rainfall generally occurs between October and
April; coastal fog is common in May and June.
2.23 GEOLOGY AND SOILS
The City of Carlsbad lies entirely within the Coastal Geomorphic Province, which occupies the
western portion of San Diego County corresponding to the region of sedimentary surface rocks. The
dominant relief of this province is a series of marine terraces also known as mesas.
According to Bowman (1973), 33 different soil series are present in the City of Carlsbad, including
sandy, cobbly, loamy, and clayey types, and soils associated with gabbro parent material and Santiago
Peak metavolcanic formations. On the coastal terraces most of the soil series are comprised of sandy
loams, clay loams, and clays. In the foothills the soils generally are well-drained sandy loams or silt
loams overlaying decomposed granitic or metavolcanic rock.
2.2.4 PLANT COMMUNITIES
Eight distinct native plant communities (Holland 1986) are present within the City of Carlsbad (see
Section 3 for details of mapping). In addition, three non-native habitat types (i.e., eucalyptus
woodland, disturbed wetland or floodplain, and disturbed habitat), open water, and development also
account for significant areas within Carlsbad (see Section 3 for discussion). These native and non-
native habitat types are discussed below with respect to their general habitat structure, species
composition, and general location within the City of Carlsbad. Terminology and definitions of the
natural communities follow Holland (1986), for the most part, with modifications to conform with
community types recognized by Ogden Environmental and Energy Services (in their Multi-species
Conservation Plan [MSCP] mapping efforts) and SANDAG (Table 2).
11
TABLE 2
Habitat Type
CLASSIFICATION SYSTEM FOR HABITAT COMMUNITIES
OCCURRING IN THE CITY OF CARLSBAD
SANDAG
Code
Holland
Code
Coastal Sage Scrubs
coastal sage scrub
disturbed coastal sage scrub
maritime succulent scrub
Chaparrals
southern mixed chaparral
chamise chaparral
southern maritime chaparral
coastal sage scrub/chaparral
Grasslands
non-native (annual) grassland
native (perennial) grassland
Saltwater Marsh
Freshwater Marsh
Sycamore Alluvial Woodland
Riparian Scrub
Oak Woodland
Eucalyptus Woodland
Open Water
Disturbed Wetland
Disturbed Habitat
Active Disturbance
Active Agriculture
Golf Course
Developed
30
31
40
52
53
60
70
82
83
90
100
123
130
140
190
200
210
240
242
243
244
250
32000
32001
32400
37120
37200
37630
37G
42200
42100
52100
52400
62400
63000
71100
Source: MSCP Habitat Type (modified from Holland 1986).
Coastal Sage Scrub
Within the City of Carlsbad, coastal sage scrub is represented by Diegan coastal sage scrub and
maritime succulent scrub, as well as disturbed forms of both types. Diegan coastal sage scrub is a
drought-deciduous community comprised of aromatic shrubs and subshrubs with a diverse understory
of annual and perennial herbs, perennial and annual grasses and grass-like plants. Diegan coastal
sage scrub occurs primarily on dry south-facing slopes and hillsides or on clay-rich soils adjacent to
chaparral or upslope from riparian woodlands. Characteristic species include coastal sagebrush,
California buckwheat, black sage (Salvia mellifera), white sage, lemonadeberry, laurel sumac, and
purple needlegrass. It also supports a variety of sensitive plant species, including California adolphia
(Adolphia califomica), ashy spike-moss (Selaginella cinerascens), San Diego sand-aster, and several
others. Sensitive wildlife species that occur primarily in coastal sage scrub include San Diego horned
lizard, orange-throated whiptail, California gnatcatcher, and coastal cactus wren. Coastal sage scrub
12
frequently occurs in a mosaic distribution with native grasslands and occasionally with chaparral. The
largest remaining tracts of Diegan coastal sage scrub are found in the vicinity of Lake Calavera,
southeast of Agua Hedionda Lagoon, and near Rancho Santa Fe Road. Maritime succulent scrub
includes a variety of succulents, such as fish-hook cactus, coast cholla, California desert thorn (Lycium
californicurri), cliff-spurge, bladder-pod, and several species of dudleya (Dudleya spp.), mixed with
typical Diegan sage scrub species. This community type is found along the remaining narrow upland
borders of the lagoons and on some west-facing slopes near the coast.
Chaparral
Three types of chaparral are recognized within the City: southern mixed chaparral, southern maritime
chaparral, and chamise chaparral. Southern mixed chaparral is a fire- and drought-adapted
community composed of a variety of woody shrubs, many of which are "stump sprouters" that
regenerate rapidly from underground undamaged tissues following fires or other ecological
perturbation. It is a heterogeneous community type — the dominant shrubs vary from site to site.
In most situations the dominants include chamise, interior scrub oak, mission manzanita, laurel sumac,
lemonadeberry, and toyon. Understory plants include rush-rose (Helianthemum scopariuni), deerweed
(Lotus scoparius), wreathplant (Stephanomeria spp.), and a variety of composites (Asteraceae).
Southern maritime chaparral is similar to southern mixed chaparral, but it occurs on sandstone. It
is the most limited chaparral type in distribution, particularly in Carlsbad, and is characterized by
several endemic shrubs, including Del Mar Manzanita, wart-stemmed ceanothus, coast spice bush, and
coastal scrub oak (Quercus dumosa). Other dominant shrubs encountered in this community are the
same as those listed above for southern mixed chaparral. Sensitive plant species encountered in
southern maritime chaparral include wart-stemmed ceanothus, summer-holly (Comarostaphylis
diversifolia var. diversifolia), Del Mar manzanita, ashy spike-moss, and western dichondra (Dichondra
occidentalis). Chamise chaparral is a community where chamise is the overwhelming dominant plant.
This species may account for over 90 percent of the relative cover. The remaining species include
shrubs and understory plants common in other types of chaparral.
Chaparral has a patchy distribution throughout the City of Carlsbad, occurring on more mesic north-
and west-facing slopes, alternating with coastal sage scrub, grasslands, and oak woodlands. The largest
and most representative patches occur immediately east of the Safety Center, southwest of Squires
Dam, at the north end of Rancho Santa Fe Road, and along El Camino Real south of Palomar
Airport Road.
Grassland
Both native (perennial) and non-native (annual) grasslands are present within the City of Carlsbad.
Native grasslands usually are small in area, frequently occurring as difficult-to-define, open patches
of habitat within coastal sage scrub. Many are associated with clayey soils. Native grasslands are
characterized by perennial bunch grasses such as needlegrass (Stipa spp.), and a variety of herbaceous
annuals and perennials such as Cleveland's shooting star (Dodecatheon clevelandii), blue-eyed grass,
fascicled tarweed (Hemizonia fasciculatum), sanicles, and mariposa lily (Calochortus spp.). This
habitat type is extremely limited in quantity within the City of Carlsbad, although small patches are
distributed throughout many areas of native vegetation. Non-native grasslands occur where native
communities have been degraded by repeated fire, grazing or mechanical disturbance, including
agriculture. These areas are dominated by a number of non-native grasses, including wild oats (Avena
spp.), bromes (Bromus spp.), and others (e.g., Gastridium ventricosum, Vulpia spp.); native grasses
are few. Other species present in non-native grasslands include invasive natives such as telegraph
weed (Heterotheca grandiflora), fascicled tarweed, doveweed (Eremocarpus setigerus), and weedy
introduced species such as Russian-thistle (Salsola australis), black mustard (Brassica nigrd) and
13
tocalote (Centaurea melitensis). Non-native grasslands are best represented in the southeastern
corner of the City and south of Palomar Airport Road at the eastern edge of the City.
Southern Coastal Salt Marsh
Southern coastal salt marsh is a wetland community that develops in low, flat estuaries at the mouths
of rivers and streams. Tidal inundation or excessive evaporation results in highly saline conditions
around the margins of lagoons, and it is under these conditions that salt marshes develop. This
community is characterized by low-growing succulents such as pickleweed, salty susan, salt-cedar, and
other halophytic (salt-tolerant) species. Salt marsh communities are highly productive systems that
function as nurseries for many species of fish and provide resources for a variety of locally resident
and migratory water birds. This community supports a variety of sensitive birds, including Belding's
Savannah sparrow, light-footed clapper rail, and California least tern. It also supports one sensitive
invertebrate - the salt marsh skipper. Within the City of Carlsbad, salt marsh habitat is present
surrounding Batiquitos Lagoon and Agua Hedionda Lagoon, although Batiquitos Lagoon is not open
to the ocean. It also occurs in limited amounts around Buena Vista Lagoon and possibly at Loma
Alta Creek. Several researchers have described distinct zones within southern coastal salt marsh (e.g.,
Zedler 1982).
Coast and Valley Freshwater Marsh
Freshwater marsh occurs in drainages, seepages, and other perennially moist low places. This
community is characterized by perennial, emergent monocots (e.g., grasses and lilies), 2-3 m (6-10
feet) tall, such as cattails and bulrushes. Understory species include curly dock, marsh fleabane
(Pluchea odorata), and a variety of hydrophytic grasses and herbs. Sensitive plants frequently
encountered in the vicinity of this community are spiny rush (Juncus acutus var. sphaerocarpus) and
San Diego marsh-elder (Iva hayesiana). Patches of this habitat are present at the upper ends of
Buena Vista, Agua Hedionda, and Batiquitos lagoons, where a mixture of plants of salt and
freshwater habitats is encountered. Smaller freshwater marshes grow around the perimeter of Lake
Calavera and within riparian scrub communities, and may be present in Loma Alta Creek.
Sycamore Alluvial Woodland
Sycamore alluvial woodland is an open to moderately closed, winter-deciduous, broadleafed riparian
woodland, dominated by well-spaced western sycamore. The community typically includes individuals
of several other tree species, including willow, coast live oak, Mexican elderberry (Sambucus
mexicana), and Fremont cottonwood. This community is best developed in broad channels of
intermittent streams, usually with a cobbly substrate. Sycamore alluvial woodland is uncommon in
Carlsbad, occurring primarily in the drainage east of the Safety Center and along a narrow drainage
south of Lake Calavera.
Riparian Scrub
As used herein, the term riparian scrub encompasses several natural and semi-disturbed wetland
communities, including mulefat scrub, southern willow scrub, and baccharis/tamarisk scrub. These
communities occur along river courses and seasonally moist drainages. In Carlsbad, some riparian
scrub communities are the result of urban or agricultural run-off. Riparian scrub typically is
dominated by willows and Fremont cottonwood, or by mulefat, broom baccharis, or tamarisk (Tamarix
sp.), an introduced species. The understory is variable depending upon canopy coverage, disturbance
history and water availability, and usually includes poison-oak, desert grape, western ragweed
(Ambrosia psilostchya), rushes (Juncus spp.), and a variety of other hydrophytic (wetland) species.
Riparian scrub is a highly productive community, contributing to nutrient recycling and the
14
maintenance of water quality, and providing habitat for numerous species. However, locally it
supports few sensitive plant and wildlife species. Characteristic well-developed riparian scrub occurs
along El Camino Real south of Batiquitos Lagoon, extending east from the mudflats at the eastern
end of Agua Hedionda Lagoon (e.g., Macario Canyon), and along the northern portion of the City
south of Highway 78 in Buena Vista Creek.
Oak Woodland
As used herein, oak woodland encompasses several closely related community types, including coast
live oak woodland, southern coast live oak riparian forest, and Engelmann oak woodland. Within
Carlsbad, this community typically is restricted to mesic north-facing slopes, shaded ravines, and
drainages. It is dominated by coast live oak, with scattered individuals of other tree species, including
western sycamore, willow, and Mexican elderberry. The understory includes toyon, laurel sumac,
California wild rose (Rosa califomicd), poison-oak, and currant (Ribes spp.). Oak woodland is fairly
limited in the City of Carlsbad; it is best developed in the drainage behind the Safety Center, both
to the north and east.
Disturbed Wetland/Floodplain
Disturbed wetland or floodplain is not a native plant community. It typically occurs where the natural
wetland vegetation has been degraded by mechanical activities or invaded by weedy, non-native
species. This habitat is characterized by open and patchy vegetation that includes both native and
introduced species. The dominant shrubs include mulefat, broom baccharis, and scattered willow
trees. Other species present in varying density include coastal goldenbush (Isocoma veneta), curly
dock, castor-bean (Ricinus communis), cockle-bur (Xanthium strumariuni), spiny rush, and pampas
grass (Cortaderia spp.).
Eucalyptus Woodland
Eucalyptus woodland also is a non-native community. It is dominated by various species of planted
eucalyptus (Eucalyptus spp.) that survived around old dwellings or in entire groves (e.g., the Hosp
Grove). The understory is usually poorly developed or absent owing to the allelopathic (toxic) effect
of eucalyptus leaves that acts to inhibit the growth of other plants. Although this habitat supports
no sensitive plant or wildlife species, it is often used for nesting by raptors and other birds or roosting
by bats.
Disturbed Habitat
As used herein, the term disturbed habitat encompasses a wide variety of open, non-native habitats
that lack permanent structures and currently support activities that prohibit the succession of native
plant communities. Four types of disturbed habitat are recognized: (1) typical disturbed habitat; (2)
active disturbed habitat; (3) active agriculture; and (4) golf courses. Typical disturbed habitat is
characterized by areas that have been graded, scraped, or subject to prior agricultural use. These
areas either lack vegetation or support weedy, introduced species such as Russian-thistle, doveweed,
Australian saltbush (Atriplex semibaccata), and black mustard. Typical disturbed habitat differs from
annual grassland by the abundance or domination of weedy species. For example, fallow agricultural
fields often become dominated by species such as Russian-thistle or black mustard. Active disturbed
habitat supports mineral extraction or other active uses that inhibit the growth of plants. Active
agriculture and golf courses are self explanatory, although what was active agriculture at this writing
may appear to be annual grassland or typical disturbed habitat in subsequent years. While these
disturbed habitat types directly support few or no sensitive plant and wildlife species, they may be
used as foraging habitat by raptors and several mammal species.
15
Developed
Developed areas are characterized by structures, parking lots, yards, roads, and a variety of buildings.
These areas support no native vegetation. Developed areas occupy the majority of the western half
of the City of Carlsbad, but occupy a considerably smaller percentage of the area east of El Camino
Real.
Open Water
Open water is aquatic habitat that lacks vascular vegetation and includes lakes, ponds, reservoirs, and
coastal lagoons and may be either fresh, brackish or saline. The area surrounding the open water is
almost always characterized by freshwater marsh, salt marsh, or riparian habitats. The largest bodies
of open water include the three major coastal lagoons (Batiquitos, Agua Hedionda, and Buena Vista),
Lake Calavera, and Squires Dam, although there are a number of artificial ponds throughout the City.
2.2.5 SENSITIVE BIOTA
A large number of plant and wildlife species recognized as sensitive, rare, threatened, or endangered
by CDFG, USFWS, California Native Plant Society (Smith and Berg 1988), or local resource agencies
and conservation groups have been documented from the City of Carlsbad. These are discussed
below. Species records come from published sources cited herein, from EIRs and other unpublished
environmental documents and technical reports reviewed for the study (see Appendix B), and from
personal communications with local biologists familiar with various parts of the City.
Sensitive Wildlife Species
Birds
Several species of birds recognized as threatened or endangered by state or federal agencies occur
within Carlsbad as overwintering individuals or resident populations. These include the light-footed
clapper rail, Belding's Savannah sparrow, and California least tern, all associated with coastal estuaries
and salt marsh habitats. The least Bell's vireo, restricted to riparian woodlands, and the federally-
proposed endangered California gnatcatcher, occurring primarily in coastal sage scrub communities
below about 1,200 feet (370 m), also have been reported from Carlsbad. The latter species is
widespread in coastal sage scrub habitats throughout Carlsbad. Other bird species that occur in
Carlsbad that are recognized as sensitive by the resource agencies include the coastal cactus wren,
Bell's sage sparrow, southern California rufous-crowned sparrow, California horned lark, and several
species of raptors.
Accipiter cooperi — Cooper's hawk
USFWS: None
CDFG: Species of Special Concern
Cooper's hawk ranges through most of California and is a common winter migrant in San Diego
County. In the county, Cooper's hawk breeds almost exclusively in oak woodland habitats; in the
winter they may be found in any woodland habitat (Unitt 1984). Mature trees in suburban areas also
may support nesting Cooper's hawks. Populations of this species have declined steadily throughout
the state probably as a result of habitat destruction, falconry, and pesticide abuse (Remsen 1979).
Riparian areas and groves of mature trees within Carlsbad meet the habitat requirements of this
species.
16
Accipiter striatus - sharp-shinned hawk
USFWS: None
CDFG: Species of Special Concern
This species is also a Bureau of Land Management and U.S. Forest Service watchlist species due to
declines in populations throughout its breeding range. The sharp-shinned hawk is a regular winter
migrant in San Diego County and may be encountered in any woodland habitat (Unitt 1984).
Riparian woodlands and suburban areas in Carlsbad represent potential habitat for this species. It
was reported from Rancho La Costa.
Aimophila ruficeps canescens — Southern California rufous-crowned sparrow
USFWS: Candidate (Category 2)
CDFG: None
The Southern California rufous-crowned sparrow is an uncommon to fairly common resident of San
Diego County primarily found in coastal sage scrub that is known to occur in the City of Carlsbad
(Unitt 1984). This species recently became a federal candidate for listing as threatened or
endangered.
Ammodramus sandwichensis beldingi - Belding's Savannah sparrow
USFWS: Candidate (Category 2)
CDFG: Endangered
Belding's Savannah sparrow ranges from Santa Barbara County, California south to about El Rosario,
Baja California, Mexico. It is a permanent resident in San Diego County (Unitt 1984). This species
nests in salt marshes or the margins of lagoons in low vegetation dominated by pickleweed.
Apparently, it prefers the upper littoral zone of tidal marshes, areas flooded only by high spring or
storm tides (Massey 1977; Unitt 1984), and it forages in marshes and nearby mudflats, beaches, rocks,
and in low coastal strand vegetation. In Carlsbad, Belding's Savannah sparrow has been reported
from Batiquitos, Agua Hedionda, and Buena Vista lagoons.
Buteo lineatus -- red-shouldered hawk
USFWS: None
CDFG: None
Audubon Society: Blue List, 1972-1986
The red-shouldered hawk is an uncommon to fairly common resident in San Diego County (Unitt
1984). It inhabits nearly the entire county west of the desert. Red-shouldered hawks occupy a
variety of woodland habitats, and stands of non-native trees (such as eucalyptus) may serve as
breeding habitat. Although concern has been expressed that the numbers of this species are
declining, Wilbur (1973) concluded that no major declines in population had occurred in California
except possibly in the Sacramento and San Joaquin valleys. These hawks can tolerate human
presence if mature trees with a high canopy are maintained; they nest in oak and riparian woodland,
suburban areas, and orchards.
Campylorhynchus brunneicapillus sandiegensis ~ San Diego (coastal) cactus wren
USFWS: Candidate (Category 2)
CDFG: Species of Special Concern
The cactus wren is a widespread and common species of the southwestern deserts, extending to the
Pacific coast in southern California and Baja California. Rea and Weaver (1990) and others previous
to them recognize a portion of the coastal population as a separate subspecies, Campylorhynchus
17
brunneicapillus sandiegensis. According to Rea and Weaver, the range of C. b. sandiegensis (the "San
Diego cactus wren") is restricted to the coastal slope of San Diego County, extreme southern Orange
County, and northwestern Baja California. Populations occurring north of southern Orange County
are assigned to the more common and widespread desert subspecies, C. b. anthonyi. Originally, all
coastal populations from the Mexican border north to Ventura County had been assigned to the
subspecies sandiegensis, but recently it has been concluded that populations in Orange, Los Angeles,
and Ventura counties more closely resemble C. b. anthonyi. It should be noted, however, that the
American Ornithological Union Committee on Taxonomy and Systematics has not yet accepted the
distinction between sandiegensis and anthonyi. Until they do so, sandiegensis should be considered
a proposed subspecies.
Cactus thickets supporting large populations of the San Diego cactus wren in San Diego County
occur primarily in sage scrub and Diegan coastal sage scrub communities, such as those found in the
vicinity of San Pasqual, Lake Jennings, Sweetwater Dam, and Otay Mesa. Smaller populations occur
at Camp Pendleton, San Elijo and Batiquitos lagoons, and Fletcher Hills. Cactus wrens also recently
(ca. 1988) occurred north of Batiquitos and Agua Hedionda lagoons (H. Wier, pers. obs.). The San
Diego cactus wren formerly was far more common in the coastal lowlands. Population declines are
linked to loss of habitat, and in particular, loss of cholla and prickly-pear cactus thickets (Hix 1990).
The San Diego cactus wren currently is being evaluated for possible listing as threatened or
endangered by the USFWS.
Cathartes aura — turkey vulture
USFWS: None
CDFG: None
Although not recognized as sensitive by the USFWS or the CDFG, the turkey vulture is considered
a declining species in San Diego County (Everett 1979). Unitt (1984) reports that this species is a
common spring and fall migrant, an uncommon to locally common winter visitor, and a rare to
uncommon summer resident in San Diego County. He further states that turkey vultures are
widespread throughout the county, particularly over open fields and grasslands.
Circus cyaneus hudsonius -- northern harrier
USFWS: None
CDFG: Species of Special Concern
On the national level, the northern harrier has been recognized as sensitive for many years by the
National Audubon Society. It ranges throughout California and may be encountered in grasslands,
open fields, and salt and freshwater marshes. According to Unitt (1984) the northern harrier is an
uncommon to fairly common migrant and winter visitor in San Diego County, and a rare and local
summer resident. This species is most common in the coastal lowlands, where as many as 10 (Tijuana
River Valley) and 19 (Sweetwater Reservoir) have been observed. Observations of displaying pairs
at Las Pulgas Creek and the Santa Margarita River suggest that small numbers of northern harriers
still breed on Camp Pendleton. Nests and nesting behavior also have been observed at French
Canyon, Sweetwater River, and Dennery Canyon.
Elanus caeruleus - black-shouldered kite
USFWS: None
CDFG: None
Although not specifically designated as rare, threatened, or endangered by either CDFG or USFWS,
the black-shouldered kite is regarded as a locally sensitive raptor. Formerly the Kelly Ranch north
of Agua Hedionda Creek supported a communal roost for approximately 15 to 25 birds (H. Wier,
18
pers. obs.). The black-shouldered kite can nest in riparian woods and large shrubs in coastal sage
scrub and chaparral.
Empidonax traillii extimus - southwestern willow flycatcher
USFWS: Candidate (Category 1)
CDFG: None
The southwestern willow flycatcher is an uncommon spring and fall migrant found throughout San
Diego County (Unitt 1984). Nesting pairs use willow thickets in riparian woodland. There are no
records of this species from Carlsbad, but it may occasionally use the same habitat in the City as used
by the least Bell's vireo in the past (i.e., Macario Canyon and Buena Vista Creek).
Eremophila alpestris actia - California horned lark
USFWS: Candidate (Category 2)
CDFG: None
The California horned lark is a common breeding resident, and an abundant migrant and winter
visitor (Unitt 1984). It is commonly found in both native and non-native grasslands, in open
agricultural land, and along sandy ocean or bay shores. The horned lark has become a candidate for
listing as threatened or endangered, apparently because of rapid development of its habitats. This
species is likely to be relatively common in Carlsbad.
Lanius ludovicianus — loggerhead shrike
USFWS: Candidate (Category 2)
CDFG: None
The loggerhead shrike is a relatively common resident of San Diego County found around agricultural
land, native and non-native grassland, and broken coastal sage scrub and chaparral (Unitt 1984). This
small raptor became a federal candidate for listing as threatened or endangered because of rapid
development of its habitats. Development not only threatens nesting areas for the shrike, but its prey
base as well (including insects, lizards, and small rodents).
Pelecanus occidentalis californicus — California brown pelican
USFWS: Endangered
CDFG: Endangered
The California brown pelican is a common to very common non-breeding visitor along the Southern
California coast (Unitt 1984). This species was listed as endangered by the state and federal
governments as a result of reproductive failures, and consequent precipitous population declines, due
to DDT contamination in the 1960s and 1970s.
This species is commonly seen along the coast and lagoons in Carlsbad.
Phalacrocorax auritus — double-crested cormorant
USFWS: None
CDFG: None
This species is a common non-breeding visitor in San Diego County (Unitt 1984). It is observed most
frequently on bays, lagoons, and estuaries along the coast (Unitt 1984), but also may be encountered
on ponds at inland localities. Everett (1979) considers the double-creasted cormorant as a "declining"
species in San Diego County. He indicates that it formerly bred at Lake Henshaw, but has not
19
nested in the county since about 1933. This species occurs at Agua Hedionda, Buena Vista, and
Batiquitos lagoons, and likely uses larger inland lakes as well.
Polioptila califomica — California gnatcatcher
USFWS: Proposed endangered
CDFG: None
The California gnatcatcher is a small gray non-migratory bird with a black tail with white edges. In
the breeding season the male has a black cap. It eats insects and builds a small, cup-shaped nest of
plant material, animal hair, and spider webs.
The present known range of the California gnatcatcher extends from an isolated population on the
Palos Verdes Peninsula of Los Angeles County, and southern Orange, western Riverside, and San
Diego counties, into northern Baja California, Mexico. It is an obligate resident of coastal sage scrub
and Riversidean (inland) sage scrub communities, although it may use adjacent disturbed, chaparral,
and riparian habitats. Individuals of this species are generally found at elevations below 800 feet
along the coast, and below 1600 feet in Riverside County (Atwood 1990). Based on average territory
size and available habitat, Atwood (1990) estimated that 1,200-2,000 pairs were resident within the
state in 1990.
A pair of gnatcatchers may forage over 6 to 45 acres of land during the breeding season (generally
the end of July to the end of June), and may forage more widely at the end that period. In Carlsbad,
gnatcatcher territories probably are less than 20 acres due to the coastal location and constrained
condition of most of the suitable habitat locations (Mock 1992).
The California gnatcatcher has no special status with the CDFG, although it formerly was listed (as
Polioptila melanura) as a second priority "Species of Special Concern." The USFWS has proposed
endangered status for the California gnatcatcher pursuant to the Endangered Species Act of 1973.
Although a decision by the USFWS on the status of the gnatcatcher originally was due in September
of 1992, the "final rule" probably will not be issued until January 1993.
In San Diego County, gnatcatcher populations are known from several sites along the coast and from
as far inland as San Pasqual, Poway, Lakeside, Escondido and Ramona. The California gnatcatcher
is widespread throughout the coastal sage scrub areas of Carlsbad. The largest populations are
concentrated in the northeastern and southeastern portions of the City.
Rallus longirostris levipes -- light-footed clapper rail
USFWS: Endangered
CDFG: Endangered
This subspecies ranges from about Santa Barbara south into northern Baja California, Mexico (Unitt
1984). In San Diego County, it is an uncommon and very localized resident of tidal salt marshes that
support large stands of cord grass (Spartina foliosa) (Unitt 1984). It may also occur in brackish
marshes dominated by cattails.
The status of the clapper rail in San Diego County has been monitored closely since about 1973 by
P. Jorgensen (Wilbur 1974; Wilbur et al. 1979) and the USFWS. Clapper rails formerly were much
more common in the County. Its range and numbers have been reduced greatly by destruction and
degradation of salt marsh habitats. Census results from 1973 through 1981 indicate that the total San
Diego County population size fluctuates between about 55 and 75 pairs; the total population in
California was 173 pairs in 1981 (Unitt 1984). In Carlsbad, the light-footed clapper rail has small
populations, but it has been reported from Batiquitos, Agua Hedionda, and Buena Vista lagoons.
20
Sterna antillarum browni — California least tern
USFWS: Endangered
CDFG: Endangered
The California least tern is a common, but very localized, summer resident and migrant in San Diego
County (Unitt 1984). This species nests colonially along the coast on barrier dunes at river mouths,
lagoon entrances, and along sandy strips. Within Carlsbad, the least tern has nested at the Agua
Hedionda, Batiquitos, and Buena Vista lagoons in the past (Unitt 1984). Threats to this species come
from development of suitable nesting areas. This forces the least tern to use fewer nesting areas, thus
increasing the risk of whole colony failure due to local predation and other disturbances.
Vireo bellii pusillus — least Bell's vireo
USFWS: Endangered
CDFG: Endangered
Least Bell's vireo is a small, gray and white, migratory songbird that inhabits willow-dominated
riparian areas of southern California and adjacent northern Baja California, Mexico (San Diego
Association of Governments 1988). It is one of four North American subspecies of Bell's vireo.
Historically, this subspecies was abundant in riverine habitats from Baja California to Tehama County
in central California (Grinnell and Miller 1944; Willett 1933), with the center of its breeding range
in the Sacramento and San Joaquin Valleys. Widespread destruction of its obligate riparian habitat
for agricultural use, livestock grazing, flood control, urban development, and various commercial uses,
in combination with increased brood parasitism by the exotic brown-headed cowbird (Molothrus ater),
decimated vireo numbers, extirpating it from the central valleys, and restricting the species to small,
fragmented populations in a fraction of its former range (USFWS 1988). By 1985, only 285 pairs
were known from 45 locations in 9 counties (USFWS 1988). In response to the unparalleled decline
of this passerine, the least Bell's vireo was listed as endangered by the CDFG in 1980, and by the
USFWS in May 1986.
The two Carlsbad records of which we are aware are males from Macario Canyon (feeding a fledgling
in 1987) and Buena Vista Creek (H. Wier, pers. obs. circa 1983).
Reptiles and Amphibians
Reptiles documented from Carlsbad that are recognized as federal Category 2 candidates for listing
as threatened or endangered by the USFWS or as Species of Special Concern by CDFG include San
Diego horned lizard, orange-throated whiptail, western whiptail, and northern red diamond
rattlesnake. Other sensitive reptiles likely to be present include two-striped garter snake, and
southwestern pond turtle. The western spade-foot toad, recognized as a Species of Special Concern
by CDFG, also has been recorded from the City.
Cnemidophorus hyperythrus beldingi — orange-throated whiptail
USFWS: Candidate (Category 2)
CDFG: Species of Special Concern
The orange-throated whiptail is a small, slender, insectivorous lizard with a bright orange patch on
its throat. It occurs in the United States and Mexico, ranging from southern California (west of the
transverse and peninsular ranges) south to about mid-way through the peninsula of Baja California.
This species has exhibited population declines in California associated with the conversion of coastal
sage scrub and dry wash habitats for agriculture, urban development, and flood control. An active
forager, the orange-throated whiptail frequents dry, often rocky hillsides, ridges, valleys, and washes
that support broken coastal sage scrub, chaparral, mule fat scrub, and grassland mixed with sage scrub
21
species. It often occurs with the more common western whiptail (C. tigris). The orange-throated
whiptail relies to some extent on the burrows of small mammals, such as the California ground
squirrel (Spermophilus beecheyi), for protection from predators and adverse environmental conditions.
This species was recorded on the Alanda project site located near El Camino Real in the
northeastern portion of the City, and from an area located south of Palomar Airport Road and west
of El Camino Real.
Cnemidophorus tigris multiscutatus - coastal whiptail
USFWS: Candidate (Category 2)
CDFG: None
The coastal whiptail is an active lizard that inhabits sparse coastal sage scrub habitat that provides
room for running (Stebbins 1985). This species avoids dense shrub vegetation and grasslands. It was
recently added to the candidate species list because of threats to its habitat by development. The
coastal whiptail is likely to occur on more open, drier south-facing slopes in Carlsbad.
Crotalus ruber — northern red-diamond rattlesnake
USFWS: Candidate (Category 2)
CDFG: None
The northern red-diamond rattlesnake inhabits coastal sage scrub, chaparral, and open woodlands
(Stebbins 1975). This species is relatively common in the coastal sage scrub community in San Diego
County. However, it was added to the federal candidate list because of threats to its habitat by
development. This species is highly likely to occur in the City of Carlsbad.
Phyrnosoma coronatum blainvillei ~ San Diego horned lizard
USFWS: Candidate (Category 2)
CDFG: Species of Special Concern
The San Diego horned lizard is a small, spiny, somewhat rounded lizard that occurs primarily in open
areas in coastal sage scrub communities. It was a common species in San Diego County until about
10 years ago (Hix 1990). Three factors have contributed to its decline: loss of habitat, over
collecting, and the introduction of exotic ants. In some places, especially adjacent to urban areas, the
introduced ants have displaced the native species upon which the lizard feeds. This species has been
recorded in the northeastern part of the City just west of Lake Calavera and to the northeast of Agua
Hedionda Lagoon.
Thamnophis hammondi - two-striped garter snake
USFWS: Candidate (Category 2)
CDFG: None
Although it currently receives no state or federal protection, the two-striped garter snake is
recognized as a threatened species by the San Diego Herpetological Society (McGurty 1980). It
occurs primarily in wetlands, particularly freshwater marsh and riparian scrub habitats. Although it
has not been reported from Carlsbad, it is likely to be resident.
Scaphiopus hammondi -- western spade-foot toad
USFWS: None
CDFG: Species of Special Concern
The western spade-foot toad is primarily a species of the lowlands, frequenting washes, floodplains
of rivers, alluvial fans, alkali flats (Stebbins 1985), temporary ponds, and vernal pools. It is considered
22
sensitive because of declines in populations associated with loss of habitat. This species has been
reported from the Woolley project.
Mammals
No mammal species presently known to occur in the City are recognized as threatened or endangered
by the USFWS or CDFG. Five federal Category 2 candidate species are highly likely to occur in
Carlsbad: the San Diego black-tailed jackrabbit, San Diego desert woodrat, southern grasshopper
mouse, Dulzura California pocket mouse, and northwestern San Diego pocket mouse. Three other
mammal species recognized as federal Category 2 candidates for listing as threatened or endangered
have a remote chance of occurring at least occasionally in Carlsbad. These include the Pacific pocket
mouse, California mastiff bat (Eumops perotis califomicus), and spotted bat (Euderma maculatum).
The Pacific pocket mouse has been recorded near the coast in the City of Oceanside but otherwise
is extremely rare within its historic range (Bond 1977). None of the bat species has been recorded
in Carlsbad, and there are relatively few suitable roosting sites for bats within the City limits. The
California mastiff bat, which has been recorded from near Lake Hodges, and the spotted bat both
require rugged, rocky areas with crevices for roosting. Both of the bats could occur in the City during
foraging bouts to take advantage of insects around agriculture and wetland areas or to utilize waters
at lakes, streams, or swimming pools.
In contrast to our knowledge of the distribution of plant and bird species, the status of many
mammals is poorly known. Most mammals are secretive and nocturnal or crepuscular (active around
dusk or twilight) and are not readily identifiable unless captured and examined close at hand. There
has been much less field work on the occurrence and distribution of mammals in the City of Carlsbad,
particularly small mammals and bats.
Lepus califomicus bennettii — San Diego black-tailed jackrabbit
USFWS: Candidate (Category 2)
CDFG: None
The San Diego black-tailed jackrabbit is found in open sage scrub habitat and grassland. It was
recently added to the federal candidate list because of threats to its habitat by development. In San
Diego County, it is known from San Marcos, Escondido, San Diego area, Jamul Creek, and the
Laguna Mountains (Bond 1977). It is highly likely to occur in Carlsbad.
Neotoma lepida intermedia — San Diego desert woodrat
USFWS: Candidate (Category 2)
CDFG: None
The San Diego desert woodrat inhabits areas with heavy growth, such as dense coastal sage scrub,
chaparral, cactus, or rock crevices. This species was recently added to the federal candidate list
because of threats to its habitat from development. In San Diego County, it is known from the
Bonsall, Mission San Luis Rey, Mission Gorge, Murphy Canyon, Murray Dam, and San Diego areas
(Bond 1977). Despite no collections specifically from the City of Carlsbad, these records essentially
surround the City and, thus, the species is likely to occur there.
Onychomys torridus ramona - southern grasshopper mouse
USFWS: Candidate (Category 2)
CDFG: None
The southern grasshopper mouse is a stout mouse with a relatively short and thick tail. This species
primarily feeds on insects, but is known to capture and devour other rodents. Grasshopper mice are
23
interesting in that they emit audible "howls" upon leaving their day burrows. The grasshopper mouse
is relatively uncommon throughout its range compared to other rodent species such as deer mice
(Peromyscus spp.). O. t. ramona is found in the lower and upper Sonoran life zones of the Pacific
slopes, and in San Diego County has been recorded from Carlsbad, Gulp Valley, Dulzura, San Diego,
San Pasqual Valley, and Tijuana River Valley (Bond 1977). Continued urbanization of the coastal
region threatens the existence of this subspecies.
Perognathus (Chaetodipus) califomicus femoralis - Dulzura California pocket mouse
USFWS: Candidate (Category 2)
CDFG: None
The Dulzura California pocket mouse typically is found on slopes dominated by chaparral or oaks.
It is a relatively common pocket mouse within its preferred habitat. It was given candidate status
apparently because of rapid depletion of its habitat in Southern California. In San Diego County,
this species has been recorded from Banner, Campo, Dehesa, Dulzura, Escondido, Pala, Rainbow,
Ramona, Palomar Mountain, San Marcos, Santee, Santa Ysabel, and Witch Creek (Bond (1977).
Because of the proximity of these records to Carlsbad (e.g., San Marcos), the Dulzura California
pocket mouse is almost certainly an inhabitant of the City.
Perognathus (Chaetodipus) fallax -- northwestern San Diego pocket mouse
USFWS: Candidate (Category 2)
CDFG: None
The northwestern San Diego pocket mouse inhabits sparse or disturbed coastal sage scrub or
grasslands with sandy soils. This species was recently added to the federal candidate list because of
threats to its habitat by development. In San Diego County, it is known from Del Mar, Dulzura,
Jacumba, Lake Hodges, Pala, San Diego area, and San Marcos (Bond 1977). Although these
collection localities do not specifically include Carlsbad, they surround it and, thus, the species is
highly likely to occur in the City of Carlsbad.
Invertebrates
Four species of butterflies that are resident or potentially resident within the City of Carlsbad are
recognized as federal Category 2 candidates for listing as threatened and endangered: Harbison's dun
skipper, salt marsh skipper, Hermes copper, and quino checkerspot. Although only the salt marsh
skipper has been documented from Carlsbad, Harbison's dun skipper and Hermes copper are highly
likely residents. Both are host specific insects and usually are encountered wherever their larval
foodplants occur. The larvae of Harbison's dun skipper feeds exclusively on San Diego sedge (Carex
spissa), which has been reported from several oak woodland and riparian areas within the City. The
larvae of Hermes copper feed on redberry (Rhamnus crocea), which is a common species throughout
much of the chaparral in the City. In addition to these sensitive butterflies, the federal Category 2
candidate globose dune beetle, a resident of coastal dunes, may be present in small remnants of dunes
along the coastal margins of the City.
Euphyes vestris harbisoni - Harbison's dun skipper
USFWS: Candidate (Category 2)
CDFG: None
Harbison's dun skipper is a medium-small, chocolate brown butterfly restricted to riparian habitats
where its larval host, San Diego sedge (Carex spissa), grows. It occurs in a series of scattered and
disjunct colonies throughout western San Diego County, extending as far north as the Santa Ana
Mountains of Orange County (Brown and McGuire 1983). The insect is single brooded (one
24
generation per year); the flight period extends from late May to early July. Several instances of
extirpation are documented for populations of Euphyes vestris in San Diego County.
Wherever Carex spissa is found, Harbison's dun skipper also is likely to be present. Carex spissa has
been documented rrom several riparian areas within Carlsbad. The most likely Carlsbad locale
supporting a population of the Harbison's dun skipper is the riparian scrub habitat along El Camino
Real in the Evans Point area.
Panoquina errans - salt marsh skipper
USWFS: Candidate (Category 2)
CDFG: None
The salt marsh skipper is restricted to the narrow coastal margin from about Santa Barbara County
south to the southern tip of Baja California, Mexico (MacNeill 1962; Donahue 1975). It is
represented by a series of disjunct and isolated populations confined to coastal estuarine or salt marsh
habitats. The single larval host is salt grass (Distichlis spicata) with which adults are commonly
associated (Emmel and Emmel 1973; Brown 1981). Owing to the apparently tolerant and invasive
nature of salt grass, some colonies of the salt marsh skipper have managed to persist despite limited
habitat alteration. Nectar sources for the skipper include heliotrope (Heliotropum cutvassavicum),
salty susan, sea rocket, deerweed, and frankenia (Frankenia salind) (Brown 1981; Busnardo 1989).
The flight period of the salt marsh skipper extends from March or April to October in most years,
in a series of overlapping generations. Population density reaches its highest in mid-to-late summer.
The salt marsh skipper is resident in several protected areas in Southern California. Because of the
reduction in acreage of the salt marsh habitat in southern California, the salt marsh skipper is
considered highly sensitive. Populations of the skipper are disappearing rapidly in Baja California
as coastal marshes are being altered for salt production and other developments.
The salt marsh skipper has been observed at the east end of Agua Hedionda Lagoon, and it is likely
to be resident in salt marsh habitats around Batiquitos and Buena Vista lagoons.
Sensitive Plant Species
Within the City of Carlsbad, 20 species of plants recognized as regionally sensitive by the California
Native Plant Society (Smith and Berg 1988) have been detected. These species are discussed below.
Acanthomintha ilicifolia — San Diego thorn-mint
USFWS: Candidate (Category 1)
CDFG: Endangered
CNPS: List IB, 3-3-2
San Diego thorn-mint is an aromatic, spring-blooming (April-May) annual, 0.5-1.5 dm tall. The
flowers occur in whorls that are subtended by several bracts armed with needlelike spines ~ thus, the
name "thorn-mint". It is restricted in distribution to San Diego County and adjacent Baja California,
Mexico. San Diego thorn-mint occurs on clay lenses of several geologic origins on mesas and slopes
below 500 m (1,600 ft) elevation and is associated with Diegan coastal sage scrub, chaparral, and
native grassland. In San Diego County, the species is known from Encinitas and San Marcos south
to Sweetwater and Otay Lakes (Beauchamp 1986). The species also is known from the higher
elevations of McGinty Mountain and Poser Mountain.
Reported from the Woolley Annexation Project, the Carlsbad Land Investors project, and Camino
Hills Mobile Home Park project.
25
Adolphia califomica — California adolphia
USFWS: None
CDFG: None
CNPS: List 2, 1-2-1
California adolphia is a moderate-sized (0.5-1.0 m) profusely branched, rigid, spiny shrub, ranging
from western San Diego County, California, south into adjacent northwestern Baja California, Mexico
(Wiggins 1980). It generally occurs on clay soils in dry canyons and on hillsides on south-facing slopes
and washes in chaparral and coastal sage scrub communities below 300 m (965 ft) elevation. It
blooms in early winter to spring (December-May). In San Diego County it has been reported from
Morro Hill, Cerro de Calavera, Agua Hedionda, Rancho Santa Fe, Mount Soledad, Bernardo, Chollas
Valley, Barrett Junction, and Proctor Valley (Beauchamp 1986). This species is threatened by
urbanization, which has reduced considerably its former range (Smith and Berg 1988).
The California adolphia has been reported from numerous localities in the City, including Arroyo La
Costa, Airport Business Center, Santa Fe Glens, La Costa Northeast Annexation, Woolley
Annexation Project, Carlsbad Highlands, the east end of Dove Lane, western portion of Rancheros,
Rancho Carrillo, Lake Calavera, Evans Point, Camino Hills Mobile Home Park, and others.
Arctostaphylos glandulosa ssp. crassifolia - Del Mar manzanita
USFWS: Candidate (Category 2)
CDFG: None
CNPS: List IB (Reinstated, see below)
Del Mar manzanita represents the coastal form of San Diego County's common burl-forming
manzanita, and it is one of several sensitive plants that are indicators of the unique and depleted
southern maritime chaparral habitat. Because of taxonomic difficulties, the California Native Plant
Society (Smith and Berg 1988) and the California Natural Diversity Data Base previously did not
recognize this taxon as sensitive. In a recent treatment of Arctostaphylos, Wells (1990) considers ssp.
crassifolia as a valid taxon representing those populations in coastal San Diego County and adjacent
northern Baja California (Munz 1974). CNPS botanist Mark Skinner has proposed to reinstate Del
Mar manzanita as a List IB species. This species was reported from Arroyo La Costa and Rancho
Carrillo, and a few others.
Artemisia palmeri - San Diego sagewort
USFWS: None
CDFG: None
CNPS: List 2, 2-2-1
San Diego sagewort is a summer-blooming (July-September) weak shrub with long (0.5-0.8 m)
wandlike stems (Munz 1974). It is restricted in distribution to San Diego County and Baja California.
It typically occurs at low elevations (below 660 m) along intermittent streams and arroyos. In San
Diego County it has been recorded from Ramona, Mt. Woodson, Del Dios, Poway, and at several
sites from Tecolote Canyon south to the international border and east to Jamul (Beauchamp 1986).
In Carlsbad this species is common in a drainage surrounded by chaparral adjacent to El Camino
Real, south of Palomar Airport Road.
26
Brodiaea filifolia — thread-leaved brodiaea
USFWS: Candidate (Category 2)
CDFG: Endangered
Thread-leaved brodiaea is a rare, herbaceous, spring-blooming (May-June) perennial, with few
grasslike leaves and violet flowers. It grows in heavy clay soils that form open areas in coastal sage
scrub and chaparral communities below about 600 m (2,000 ft). It is found primarily in grassland and
vernal pool habitats. In San Diego, thread-leaved brodiaea is known from Alta Loma Creek, Vista,
Thibodo Ranch, Buena, San Marcos Hills, and Agua Hedionda (Beauchamp 1986). This species was
reported from the Camino Hills Mobile Home Park project and west of Calavera Hills, and has been
the subject of a revegetation program at the Camino Hills site.
Brodiaea orcuttii -- Orcutt's brodiaea
USFWS: Candidate (Category 2)
CDFG: None
CNPS: List IB, 1-3-2
Orcutt's brodiaea is a herbaceous, spring-blooming (April-July) perennial that grows from a corm.
It is found only in San Diego County, the Santa Rosa Plateau in Riverside County and northern Baja
California, Mexico (Wiggins 1980). It occurs in association with vernal pools, streams, and seeps.
In San Diego County, the species occurs infrequently in coastal and foothill regions below 1,500 m
(4,827 ft) elevation. Reported localities include the Santa Margarita Mountains, San Marcos, Poway,
Henshaw Dam, Santa Ysabel, Cuyamaca Mountains, Miramar Naval Air Station, Ramona,
Buschalaugh Canyon, Japatual Valley, Woodwardia Canyon, Cedar Canyon, Otay Mountain, Tecate
Mountain and lower Otay Reservoir (Beauchamp 1986). This species was reported from Arroyo La
Costa.
Ceanothus verrucosus — wart-stemmed ceanothus
USFWS: Candidate (Category 2)
CDFG: None
CNPS: List 2, 1-2-1
Wart-stemmed ceanothus is an erect, stiff-branched, rounded, evergreen shrub, 1.0-3.0 m tall, that
occurs on dry hills and mesas in coastal and mixed chaparral habitats below 300 m (965 ft) in western
San Diego County and adjacent Baja California, Mexico. It is a spring-blooming species, flowering
from January to April (Munz 1974). Beauchamp (1986) reports this species from Agua Hedionda,
Encinitas, Leucadia, Torrey Pines State Reserve, Kearny Mesa, Lake Hodges, and Point Loma. In
Baja California wart-stemmed ceanothus ranges from the Pacific coast to the foothills of the Sierra
Juarez and Sierra San Pedro Martir (Wiggins 1980). This species was reported from several areas
in the City, including Arroyo La Costa, Rancho La Costa, and the south end of Batiquitos Drive.
Comarostaphylis diversifolia ssp. diversifolia — summer-holly
USFWS: Candidate (Category 2)
CDFG: None
CNPS: List IB, 2-2-2
Summer-holly is a large shrub generally occurring on north-facing canyons and slopes and in sandy
washes in chaparral and foothill habitats below 700 m (2,297 ft) in scattered locations from the Pacific
coast in San Diego County south into Baja California. Reported localities in the County include San
Marcos Mountains, Mount Whitney, Rancho Santa Fe, Gonzales Canyon, Encinitas, Mount Soledad,
Penasquitos Canyon, Del Mar Heights, Iron Mountain, canyons of Mission Valley, Jamul Valley, and
27
Otay Mountain (Beauchamp 1986). This species was reported from Arroyo La Costa, the Airport
Business Center, and Rancho Carrillo.
Corethrogyne filaginifolia var. linifolia - Del Mar Mesa sand aster
USFWS: Category 2 (candidate)
CDFG: None
CNPS: List IB, 3-2-3
The Del Mar Mesa sand aster is a slender, erect, summer-flowering (July-September), perennial herb,
0.2-0.4 m in height, with narrow, linear leaves. This species is endemic to coastal San Diego County,
California. Although Munz (1974) indicates that it is common on bluffs and brushy slopes near the
sea in Diegan coastal sage scrub and chaparral, Beauchamp (1986) indicates that it is occasional in
sandy and disturbed places below 150 m (480 ft), and only along the coast. Beauchamp (1986)
records it from Carlsbad, Encinitas, Del Mar, Del Mar Heights, and Torrey Pines State Reserve.
Beauchamp (1986) also lists two localities that are unlikely and should be verified (J. C. Dice, pers.
comm.): Fort Rosecrans and San Diego Bay. These specimens probably are C. f. var. incana. It is
likely that Del Mar Mesa sand aster has been extirpated from some of these historical localities.
According to Smith and Berg (1988), as a component of maritime chaparral, Del Mar Mesa sand aster
is threatened by development.
Dichondra occidental^ — western dichondra, western pony foot
USFWS: Candidate (Category 3C)
CDFG: None
CNPS: List 4, 1-2-1
Western dichondra is a low perennial herb generally occurring on dry slopes, often as an understory
plant, in Diegan coastal sage scrub and chaparral. It often proliferates on recently burned slopes.
The species is found in coastal San Diego and Orange counties, on some of the Channel Islands, and
in northern Baja California, Mexico. In San Diego County, western dichondra is encountered
frequently in intact vegetation from Del Mar to Agua Hedionda, south to the international border.
Because of its fairly wide distribution and relative abundance in San Diego County and elsewhere,
this species is not particularly sensitive. This species was reported from Airport Business Center,
Evans Point, and Carlsbad Highlands.
Eryngium aristulatum var. parishii — San Diego button-celery
USFWS: Candidate (Category 1)
CDFG: Endangered
CNPS: List IB, 1-3-2
San Diego button-celery is a prostrate or decumbent (lying down) biennial or perennial species that
occurs in or near vernal pools in Riverside and San Diego counties and in northern Baja California,
Mexico. It blooms from March through July. In San Diego County it has been recorded from Camp
Pendleton, San Marcos, Miramar Naval Air Station, Clairemont Mesa, College Grove, and Otay Mesa
(Beauchamp 1986). The high sensitivity rating, combined with the limited habitat occupied by this
species, make it a vulnerable and important resource. In Carlsbad, San Diego button-celery was
reported in a vacant field south of the Carlsbad Sewage Treatment Plant adjacent to Interstate 5 (C.
Rieser, pers. comm.).
28
Euphorbia misera — cliff spurge
USFWS: None
CDFG: None
CNPS: List 2, 2-2-1
Cliff spurge is a moderately large (0.3-1.0 m) irregularly branched shrub that occurs along sea bluffs
and in coastal sage scrub. This species is distributed from Orange and Riverside counties, California,
to Baja California, Mexico, and on San Clemente and Santa Catalina Islands. In San Diego County,
cliff spurge occurs from about Carlsbad south to the international border. It is relatively common,
but extremely local in southwestern San Diego County. In adjacent Baja California, it extends south
almost to the 28th parallel (Wiggins 1980).
Cliff spurge is known from one locality in Carlsbad -- a small patch of maritime succulent scrub north
of Windsong Shores.
Fritillaria biflora — chocolate lily or mission bells
USFWS: None
CDFG: None
CNPS: Considered, but rejected: Too common
Chocolate lily is a small herbaceous perennial, 15-40 cm in height, with large, nodding, dark brown
to greenish purple, bell-shaped flowers. It is in bloom from about January through April. Chocolate
lily is occasional on open slopes with clay soils in native grassland and sparse coastal sage scrub
communities below about 700 m (2,297 ft). It ranges from San Diego and Riverside counties north
to Mendocino County (Munz 1974). In San Diego County it has been recorded from upper San
Onofre Canyon, San Marcos, Rancho Santa Fe, Bernardo, Del Mar, San Diego, Point Loma, Dehesa,
McGinty Mountain, Santee, and several other localities (Beauchamp 1986). Although the chocolate
lily has a relatively broad distribution in coastal California, the fact that it is restricted to native
grasslands, a rare and depleted habitat, suggests that it should be considered a sensitive species. In
Carlsbad, this species has been reported from Bressi Ranch (south of Palomar Road/east of El
Camino Real).
Harpagonella palmeri var. palmeri - Palmer's grappling-hook
USFWS: None
CDFG: None
CNPS: List 2, 1-2-1
This widely-distributed, diminutive annual occurs in Los Angeles, Orange, Riverside, and San Diego
counties, and also on San Clemente Island, in Arizona, in Baja California, and in Sonora, Mexico.
It typically grows on clay soils and burns below 1,000 m (3,280 ft) elevation, and flowers from
February to April (Munz 1974; Wiggins, 1980; Beauchamp 1986). In San Diego County, Palmer's
grappling hook is reported in Guajome Mesa, Rancho Santa Fe, Olivenhain, Poway Grade, Kearny
Mesa, Emerald Hills, Mission Gorge, Otay, Dehesa, Rice Canyon, Table Mountain, and Box Canyon
(Beauchamp 1986). This species was reported from Calavera Hills.
Iva hayesiana -- San Diego marsh-elder, poverty weed
USFWS: Candidate (Category 2)
CDFG: None
CNPS: List 2, 2-2-1
This low perennial shrub occurs in southwestern San Diego County and northern Baja California
(Munz 1974; Smith and Berg 1988). It grows in low-lying, moist or alkaline places along intermittent
29
streams in coastal areas. Although it has a fairly restricted range in San Diego County, San Diego
marsh-elder is apparently more widespread to the south, ranging into central Baja California (Wiggins
1980). San Diego marsh-elder often grows in association with spiny rush and other indicators of
wetland habitat (Reed 1988). San Diego marsh-elder may be a dominant understory plant in
disturbed floodplain situations such as that in the Otay River Valley. Its habitat in southwestern San
Diego County is threatened by coastal development and channelization of local streams and rivers.
Muilla clevelandii — San Diego golden-star
USFWS: Candidate (Category 2)
CDFG: None
CNPS: List IB, 2-2-2
San Diego golden-star is found only in southern San Diego County and adjacent northwestern Baja
California, Mexico. This spring-blooming (March-May), herbaceous perennial occurs infrequently on
clay soils on dry mesas and hillsides and among vernal pools in Diegan coastal sage scrub or chaparral.
Primary threats to this species are illegal dumping, off-road vehicle activity, and urbanization (Smith
and Berg 1988). A survey of herbarium specimens collected in the past century and deposited at the
San Diego Natural History Museum indicates that few previous localities for this plant still exist in
an undeveloped state or condition otherwise suitable for supporting populations of this plant. Extant
populations include those in vernal pool habitats on Naval Air Station Miramar, west of Rancho
Bernardo, and San Ysidro Mountains. In Carlsbad, large populations occur on the Rancheros
property and south of Rancho Santa Fe Road.
Juncus acutus var. sphaerocarpus - spiny rush
USFWS: None
CDFG: None
CNPS: List 4, 1-1-3
This large (0.5-1.5 m), tufted, perennial rush, with stout, rigid stems, is encountered frequently in
alkaline seeps and marshes or in areas adjacent to these. Spiny rush has a wide distribution from San
Luis Obispo County south to Baja California and east to Imperial County and Arizona, although
some doubt exists regarding the taxonomy of eastern populations. Although urbanization represents
a serious threat to spiny rush (Smith and Berg 1988), the abundance of this plant in many widely
separated wetlands, together with the current application of protection for these habitats, indicates
a rather low threat to this species. This species was reported from the La Costa Development,
Batiquitos Pointe Site, west side of Batiquitos Lagoon, Lake Calavera, Buena Vista, Evans Point,
Buena Vista Creek, and other locations.
Quercus engelmannii -- Engelmann oak
USFWS: None
CDFG: None
CNPS: List 4, 1-2-2
Engelmann oak is a moderately large tree with gray-green foliage, whitish and shallowy furrowed
bark, and an open, airy appearance. It generally occurs on mesas and open slopes in foothill and
coastal areas below about 1,300 m (4,200 ft), in San Diego, Riverside, and Orange counties and
northern Baja California. It may occur in closed canopy riparian woodlands dominated by coast live
oak or in more monotypic stands as an oak savanna on moist north-facing slopes. This oak occupies
the smallest range of any oak tree in the southwestern United States (Scott 1990); the center of its
distribution is cismontane San Diego County. Engelmann oaks are sensitive to land management
practices such as fire, and their small, disjunct woodlands are highly susceptible to extirpation.
Individual trees typically live from 50 to 80 years; however, a few trees in every woodland may be 150
30
to 350 years old (Scott 1990). This species was recorded from the woodland areas south of Palomar
Airport Road west of El Camino Real (SW Quad).
Selaginella cinerascens — ashy spike-moss or mesa clubmoss
USFWS: None
CDFG: None
CNPS: List 4, 1-2-1
This tiny, prostrate, whitish gray, moss-like plant occurs in San Diego County and adjacent
northwestern Baja California, Mexico. In San Diego County it ranges from about Rancho Bernardo
south to the international border. It is relatively abundant in coastal areas, occurring on flat mesas
below 300 m (965 ft), that are prime locations for housing. Development of these areas has caused
massive reduction of the habitat of the ashy spike-moss. Although this plant is one of the most
common understory plants in Diegan coastal sage scrub and coastal chaparral communities, its
extremely restricted geographical range and the rapid disappearance of its primary habitats combine
to make it a sensitive resource. This species was reported from Arroyo La Costa, Airport Business
Center, Woolley Annexation Project, Carlsbad Highlands, western side of Rancheros, intersection
(NW) of Alga Road and El Camino Real, north of N end of Ambrosia Lane, Rancho Carrillo, and
Evans Point.
Solarium tenuilobatum — narrow-leaved nightshade
USFWS: Candidate (Category 2)
CDFG: None
CNPS: List IB, 3-1-3
This purple-flowered, low, woody shrub occurs infrequently between 200 and 1,100 m (656 to 3,610
ft) elevation in chaparral habitats in southern San Diego County and Baja California. It is known
from Jamul, Lyons Valley, Otay Mountain, Potrero Grade, Barrett Dam, Silverwood, Campo
(Beauchamp 1986), the east slope of San Miguel Mountain (PSBS 1980), the eastern end of the
Sweetwater River Valley, and near Mussey Grade Road near Ramona (F. T. Sproul, pers. comm.).
This species was reported from Carlsbad Highlands.
Other Key Species
In addition to sensitive wildlife and plant species, there also are several key wildlife species whose
presence in Carlsbad reflect the overall health and viability of the City's natural resources. A sample
of these species includes mule deer (Odocoileus hemionus), bobcat (Felis rufus), gray fox (Urocyon
cinereoargenteus), coyote (Canis latrans), and golden eagle (Aquila chrysaetos). The conservation
program and preserve system developed by the City should consider the requirements of these species
as well.
31
SEC! ON 3
Resource Inventory and Mapping
BIOLOGICAL RESOURCES AND HABITAT ANALYSIS
in support of the CITY OF CARLSBAD HABITAT MANAGEMENT PLAN
SECTION 3
RESOURCE INVENTORY AND MAPPING
3.1 INTRODUCTION
The resource analysis for the HMP focused on two major biological tasks: (1) accumulation of a
biological inventory and mapping of habitats and sensitive species present within the City of Carlsbad;
and (2) identification of a potential interconnected preserve system to accommodate both relatively
common and sensitive biological resources. This section details the methods and results of the first
task. The second task included analyses of habitat value and habitat sensitivity, which are described
in detail in Section 4.
The study focused on undeveloped areas within Carlsbad, with particular emphasis on large and/or
connected areas of undisturbed native habitat. The majority of the data for the biological resource
analysis was obtained by reviewing environmental documents, topographic maps, and aerial
photographs made available through the City of Carlsbad, resource agencies, and landowners/
developers. A limited amount of field surveys were conducted to check the accuracy of the mapping
efforts. Data from areas immediately adjacent to the City of Carlsbad (i.e., Encinitas and San
Marcos) also were reviewed, because of their relevance to establishing wildlife corridors and habitat
linkages to offsite open space areas.
3.2 MATERIALS
Data for the biological inventory and mapping effort were obtained from a variety of sources. The
primary source of data was the library of the City of Carlsbad, which includes over 50 biological
resources reports from EIRs and other environmental documents for projects proposed within the
City from 1978 to present (see Appendix B). Because the reports represent a variety of proposed
developments, have been written by a variety of biologists, and cover a wide range of years, they are
highly variable in their thoroughness and coverage. Most of the reports include vegetation maps,
locations of sensitive species, lists of plant and wildlife species observed, and descriptions of habitat
types.
Additional data regarding sensitive species and habitats present within the City of Carlsbad were
obtained from the California Natural Diversity Data Base (CNDDB) (USGS quadrangles San Luis
Rey, San Marcos, Encinitas, and Rancho Santa Fe), the California Native Plant Society's Inventory
of Rare and Endangered Vascular Plants (Smith and Berg 1988), Report on the California Butterflies
Listed as Candidates for Endangered Status by the USFWS (Murphy 1990), Beauchamp (1986),
discussions with local experts, and available information regarding the distribution of vernal pools in
San Diego County (Bauder 1986).
Other materials consulted included soil maps from Bowman (1973), a 7.5' x 7.5', 500-scale (1"=500')
color aerial photograph of the City (Aerial Fotobank, Inc., 6 February 1988), and a set of 23 400-
scale (1"=400') blueline aerial orthophotos prepared by Fraser Engineering from aerial photographs
dated September-October 1988. The blueline orthophotos were produced from a set of mylars owned
by the City of Carlsbad.
3.3 METHODS
A preliminary vegetation map was generated based on photo interpretation by circumscribing
vegetation communities (polygons) on the 400-scale blueline orthophotos using existing vegetation
32
maps from biological resources reports and observed distributions of vegetation types on the
orthophotos. Figure 3 illustrates the total area from which field-generated vegetation maps were
available. During this task, soils maps (Bowman 1973) and the 500-scale color aerial photograph were
consulted to help define vegetation boundaries. Reconnaissance level field surveys were conducted
by John Brown, Ph.D. (Dudek & Associates) and Sarah Rick (Michael Brandman Associates) in areas
within the City where vegetation maps were incomplete, incompatible, or lacking. During the field
surveys, any sensitive plant or animal species encountered were noted and incorporated into the data
base. Terminology for vegetation communities employed are standardized community types as
adopted by SANDAG for their GIS efforts. These communities types follow Holland (1986) for the
most part, and are listed in Table 2.
The 23 completed 400-scale vegetation maps were photo-reduced and combined to produce a 1,000-
scale (1"=1,000') mylar of the preliminary vegetation map. The map was made available to private
and public agencies and landowners/developers. Several planners, property owners, and developers
(e.g., Hoffman Planning Associates, Fieldstone Company, etc.) submitted more detailed or more
recent versions of the portion of the map that included their ownerships or planning areas. Each of
these submissions were subject to field review before incorporation into the final vegetation map.
During this review period, several other recent environmental documents became available (e.g., Lake
Calavera EIR, Rancho Santa Fe Road EIR, Carrillo Ranch EIR, and the Aviara EIR), thus allowing
further fine-tuning of the preliminary vegetation and sensitive species maps.
A final set of 400-scale blueline maps of the vegetation communities was produced incorporating all
of the data received. Clear mylars of the vegetation polygons were made by tracing vegetation lines
from the 400-scale bluelines calibrated with the originals of the City of Carlsbad orthotopo mylars.
Each polygon was labelled by a number code representing a specific community type (see Table 2).
The clear mylars with vegetation boundaries and reference points were submitted to SANDAG for
digitization. The vegetation plots produced by the SANDAG GIS system were submitted to team
biologists to check the accuracy of presentation and adherence to the original orthophoto mapping.
Locations of sensitive plant and wildlife species were transcribed onto the 400-scale bluelines
orthophotos from existing biological documents. Sensitive species observed during field checking of
the vegetation maps also were recorded on the maps. Also, all publicly available information
regarding the distribution of the California gnatcatcher, as made available by Sweetwater
Environmental biologists, were incorporated into the map. Locations of sensitive species were
transferred onto the clear mylars of the vegetation communities and digitized by SANDAG
subsequent to digitization of the vegetation communities. Locations of most sensitive species were
identified by a point. However, large stands of specific sensitive plant species (e.g., California
adolphia and Del Mar manzanita) were identified by small polygons.
3.4 RESULTS
3.4.1 VEGETATION MAP
It is important to understand that the vegetation map was generated through photo interpretation
of blueline orthophotos and existing vegetation maps from EIRs and other available technical
documents. A limited amount of field work was conducted to field-check the accuracy of the maps.
There are areas of the City that have not been surveyed beyond the photo interpretation provided
here. This methodology is adequate to develop a general vegetation map, but is not intended to
provide precise, site-specific vegetation information. Also, this methodology does not allow for
vegetation descriptions more precise than the plant community level. To satisfy the requirements of
the California Environmental Quality Act (CEOA), specific project areas will require focused field
33
surveys to fine-tune the information provided here, characterize the general biological resources of
the site, and provide site-specific analyses of sensitive resources.
Table 3 presents acreage by aggregated vegetation type for the City. More than 10,000 acres (40.9
percent) of the City of Carlsbad were mapped as developed. Approximately 10,200 acres (41 percent)
of the City still support natural habitat. Of the natural habitat, approximately 7,150 acres (70
percent) are comprised of native habitats. Although there is natural habitat distributed throughout
the City, the largest areas of contiguous habitat generally are located in the eastern portion of the
City. With the exception of the lagoons, the western portion of the City is mostly developed or
supports disturbed habitat.
TABLE 3
ACREAGES BY AGGREGATED VEGETATION TYPES WITHIN THE
CARLSBAD HABITAT MANAGEMENT PLAN STUDY AREA
Vegetation/Land
Cover
Coastal Sage Scrub
Disturbed Coastal Sage
Scrub
Chaparral
Non-Native Grassland &
Disturbed Grassland
Native Grassland
Salt/Freshwater Marsh
Oak Woodland & Sycamore
Alluvial Woodland
Eucalyptus Woodland
Open Water
Disturbed Wetland
Disturbed Habitat, Active
Agriculture, Golf Course
Developed
Study Area
3,018
638
2,409
2,619
23
372
709
305
1,172
190
4,986
11,987
Percent
of Total
10.6
2.3
8.5
9.2
0.1
1.3
2.5
1.1
4.1
0.7
17.3
42.3
City
2,503
633
1,727
2,449
22
358
618
302
1,102
190
4,545
10,191
Percent
of Total
10.0
2.5
8.1
9.8
0.1
1.4
2.5
1.2
4.4
0.8
18.2
40.9
TOTAL 28,337 100 24,940 100
Sensitive habitats present within the City include 3,149 acres (12.6 percent of the City) coastal sage
scrub (including maritime succulent scrub and disturbed coastal sage scrub), 22 acres of native
grassland, 358 acres of salt- and freshwater marsh, and 618 acres of oak and sycamore alluvial
woodlands. Chaparral, including southern mixed chaparral, chamise chaparral, southern maritime
chaparral, and coastal sage scrub/chaparral, occupies about 1,727 acres (8.1 percent of the City).
Among the subtypes of chaparral, southern maritime chaparral is considered sensitive by local and
regional resource agencies.
34
3.4.2 SENSITIVE SPECIES MAP
As with the vegetation map, it is important to note that the existing sensitive species information for
the City is limited. The information provided here comes from published information, existing EIRs
and other technical reports, and from communications with local biologists. While the data base is
reasonably good for plants and birds, information on sensitive reptiles and amphibians, for example,
is relatively poor — even for previously surveyed areas ~ because these species are often difficult to
detect. Other areas have not been surveyed for sensitive species at all. Therefore, the sensitive
species map can only be interpreted as evidence of positive findings. The absence of sensitive species
may indicate areas inadequately surveyed or not surveyed at all.
The results of the sensitive species mapping are presented in Figure 4. The most widespread sensitive
plant species within the City include California adolphia and ashy spike-moss, primarily in coastal sage
scrub; and wart-stemmed ceanothus, summer-holly, and Del Mar manzanita, primarily in southern
maritime chaparral. In drainages and riparian areas spiny rush is fairly common. Other sensitive
plants encountered less frequently include San Diego golden-star, western dichondra, Engelmann oak,
San Diego sagewort, San Diego marsh-elder, San Diego thorn-mint, and thread-leaved brodiaea.
The most widespread sensitive wildlife species present in the City is the federally-proposed
endangered California gnatcatcher. This species is resident nearly everywhere that coastal sage scrub
occurs. Figure 4 illustrates 113 gnatcatcher records, which includes both singletons and pairs. While
recording absolute numbers is useful for quantifying the presence and distribution of the species in
the City, it is important to note that numbers fluctuate from season to season and year to year, and
that not all areas of the City have been thoroughly surveyed. Dr. Pat Mock of Ogden Environmental
and Energy Services suggests that, based on a density estimate of one pair per 15 acres (which is an
average home range in the San Diego area) and approximately 2,500 acres of coastal sage scrub in
the City, Carlsbad could support as many as 166 pairs (P. Mock, pers. comm.). Thus, the number
of gnatcatchers in the City is at minimum 113, with perhaps as many as 166.
Other sensitive wildlife species encountered infrequently within the City include San Diego horned
lizard and orange-throated whiptail in coastal sage scrub; California least tern, Belding's Savannah
sparrow, and light-footed clapper rail in estuaries and salt marsh areas; and least Bell's vireo in willow
riparian habitat. Although not represented in the sensitive species map, the California brown pelican
and California least tern are common along the coast and in the lagoons in Carlsbad.
35
SECT ON 4
Biological Preserve Planning Area
and Design Approach
BIOLOGICAL RESOURCES AND HABITAT ANALYSIS
in support of the CITY OF CARLSBAD HABITAT MANAGEMENT PLAN
SECTION 4
BIOLOGICAL PRESERVE PLANNING AREA AND DESIGN APPROACH
4.1 INTRODUCTION
A critical component of the HMP for the City of Carlsbad is the identification of areas within the
City limits that are suitable for a system of biological preserves, conservation, or management areas.
This section provides a discussion of the features used to identify biologically valuable areas. These
factors then are incorporated in a quantitative methodology used to rank areas of the City in regard
to their biological value, rarity, and uniqueness. The results obtained from the ranking method will
form the basis for future decisions concerning habitat evaluation, acquisition, and implementation and
management of an HMP that are consistent with the City's General Plan, as well as state and federal
conservation planning efforts (e.g., NCCP and Habitat Conservation Plans [HCP]).
It is important to consider the conservation effort of the City in the context of other planning efforts
in San Diego County and the Southern California region (e.g., the MSCP, the North County MHCP,
and the NCCP for coastal sage scrub). Carlsbad, by itself, likely does not have enough remaining
natural habitat to conserve any of the sensitive habitats or species of concern occurring in the City
in perpetuity (100- or 200-year survival with a 95 percent probability are common definitions of
perpetuity used by conservation biologists). However, by developing an HMP that is consistent with
other conservation planning efforts, and through mutual cooperation with other jurisdictions in the
region, Carlsbad can make a significant contribution to the conservation of native habitats and species
in Southern California. Within this context, therefore, the HMP does not purport to provide a
comprehensive, stand alone preserve system for sensitive habitats and species. Rather, the purpose
of the HMP is to provide a program that contributes to overall conservation efforts and maintenance
of functional ecosystems in Southern California.
4.2 PRESERVE DESIGN LITERATURE REVIEW
4.2.1 SIZE
Much of the literature on the design of nature preserves has focused on the physical characteristics
of the preserves, including their shape, size, and degree of isolation from other areas of natural
habitat. When the primary goal of a preserve system is to minimize the probability of extinction of
its component species and maintain a functional ecosystem, larger preserves are more effective than
smaller ones. In isolated patches of habitat, it has been shown empirically and theoretically that the
rate of species extinction is inversely related to patch size (Diamond 1975; Wright and Hubbell 1983;
Usher 1987; Soule 1991). The preserve size required to maintain various kinds of ecosystems is
poorly understood and requires much more scientific study. In general, the smaller the preserve, the
greater the level of protection and hands-on management it will require to remain viable (Noss 1983).
There are several reasons why large preserves may be superior to small ones. Smaller preserves
necessarily support smaller populations of organisms. These small populations are more prone than
larger ones to chance fluctuations in birth and death rates which, when extreme, can lead to local
extinction (Wilson and Willis 1975; Shaffer 1981; Jensen 1987). Small populations also will lose
genetic variation as a consequence of genetic drift more rapidly than large populations (Franklin
1980; Lacy 1987). Loss of genetic variation can negatively affect a population of organisms because
it results in higher levels of homozygosity, a condition in which a pair of genes at a particular location
on a chromosome are alike. Homozygosity can be associated with poor growth, higher frequencies
36
of disease, and decreased survival during periods of stress (Soule and Simberloff 1986). Over the
longer term (from decades to thousands of years), depletion of genetic variation in small populations
can lead to an inability to adapt to changing environmental conditions, and ultimately to population
extinction (Lacy 1987; Lande and Barrowclough 1987).
4.2.2 SHAPE
The shape of a preserve also can influence its ability to effectively conserve native species. At their
borders, nature preserves often will be subject to negative influences or "edge effects" from the
outside, including increased levels of predation and nest parasitism (e.g., cowbirds laying eggs in vireo
nests), microclimatic changes (e.g., increased sunlight and temperature), and direct destruction of
native vegetation and wildlife by human uses (Schonewald-Cox and Bayless 1986; Yahner 1988).
Edge effects are strongest on habitat fragments that are small and irregularly shaped (Forman and
Godron 1981; Laurence and Yensen 1991). Several studies have considered the effect of increasing
perimeter relative to preserve size using a variety of quantitative measures (Faeth and Kane 1978;
Game 1980; Blouin and Conner 1985). Although the relationship between preserve shape and
immigration and emigration rates requires further investigation, it is generally true that preserves that
are circular in shape will have the least amount of edge for their size and thus will be least vulnerable
to edge effects. The extent and severity of edge effects ultimately will depend on the nature of the
habitat surrounding a preserve. In urban areas where immediate threats from "human-commensal"
species (e.g., pets and some pest species) exist at the edges of preserve boundaries (Murphy 1988;
Soule et al. 1988), the ratio of edge to interior probably should be minimized whenever possible.
4.2.3 ISOLATION/WILDLIFE CORRIDORS
The degree of isolation of individual preserves also is an important design consideration, and in some
cases, may be at least as significant for the maintenance of regional biodiversity as overall preserve
size (Noss 1983). Both demographic (considering factors such as population size, reproduction,
mortality, emigration, and immigration) (Fahrig and Merriam 1985; Burkey 1989) and genetic
(Boeklen 1986; Boeklen and Bell 1987; Lacy 1987) models predict that higher levels of migration
between preserves will lead to lower probabilities of extinction. Only modest levels of migration (one
or two migrants per subpopulation per generation) may be required to mitigate the negative genetic
effects of population fragmentation (Lande and Barrowclough 1987). These models lead to the
design recommendation that isolated preserves be located as close together as possible in order to
facilitate exchange of individuals between subpopulations (Diamond 1975; Wilson and Willis 1975).
For species reluctant or unable to move through non-natural habitats (e.g., golf courses or agricultural
fields), the incorporation of habitat linkages (e.g., a wildlife corridor) into the design of a preserve
system is critical. Although empirical research on the optimal design for linkages is lacking, computer
simulations have been useful in identifying some of the basic factors that may influence habitat
linkage utility. Effective linkages must be wide enough to resist edge effects, contain the appropriate
habitat(s) of the key species expected to travel through them or use them for dispersal, possess
adequate cover to prevent excessive predation on migrants or dispersers, and contain as few turns or
other barriers to movement or dispersal as is feasible (Soule and Gilpin 1991). In addition, networks
of several habitat linkages probably provide a better system for migration and dispersal than single
connections because alternative routes are available (Forman and Godron 1981; Noss 1987).
4.2.4 BUFFERS AND DISTANCE SETBACKS
In order to maintain the integrity of biological resources adjacent to development or other land uses
generally considered incompatible with biological resource areas (e.g., active recreation areas that
receive heavy human use), the interface between natural open space and development (sometimes
37
called the natural/urban interface) must include an appropriate buffer area. Strictly defined, the
"buffer" includes the area between the open space boundary and the boundary of a specific
development or land use. It is assumed that habitat within the buffer area will be degraded by
human-caused disturbance and, thus, the area should not be considered part of the "preserve".
Various approaches have been taken to quantify disturbance from development and specify
appropriate buffers for biological resources in Southern California (Scott 1992; Sauvajot 1992; Kelly
and Rotenberry 1992). It is clear that no single approach or specific buffer distance will satisfy the
buffer needs for different resources under different levels of pressure from development. In San
Diego, for example, a table of distance setbacks between land-use types and biological resources was
developed by Pacific Southwest Biological Services (PSBS). A comparable set of guidelines has been
developed for the San Diego County Resource Protection Ordinance (RPO). However, the
recommended buffer distances deviate greatly between the two lists. Dudek & Associates has
developed a set of buffer values that represents a compromise between the PSBS and RPO
recommendations. The ranges of buffers are meant to provide a general guideline and are not
intended to act as rigid standards. Also, these guidelines derive from qualitative input from
experienced field biologists and do not come from scientific field studies. Unfortunately, thoroughly
tested and validated field data do not exist at this time, although ongoing studies should provide some
data on the question of buffers in the next two to four years (Scott 1992; Sauvajot 1992). Each
specific natural/urban interface should be evaluated independently considering the guidelines and the
biological sensitivity of the habitat and wildlife species adjacent to development.
Flexibility in setback distance is necessary to reasonably and logically accommodate the varying quality
or sensitivity of resources within natural open space adjacent to proposed land uses. For example,
buffer width should be greater between high quality coastal sage scrub and residences, because high
quality coastal sage scrub is likely to support more sensitive species. Narrow riparian corridors may
require wider buffers than broad riparian corridors in order to allow comparable unobstructed open
space to facilitate wildlife use and movement. Topographic barriers, such as canyons, rock outcrops,
steep slopes, and elevational differences, may render prescribed buffer distances inappropriate.
Finally, simple linear calculations or formulas for buffers may be inappropriate when development
patterns create variations in the contour of the natural urban interface. For example, a development
with an undulating boundary or corners at acute angles (i.e., less than 90 degrees) will result in open
space peninsulas which share more border with the development than a development with square
angles. In this situation, the buffer would have to be greater to compensate for the greater interface
area.
Ideally, no recreational activities or active land uses would be permitted within buffer areas. In some
buffer areas, however, passive recreation may be an acceptable use. Whether recreational activities
are acceptable in certain buffers will depend on the characteristics of the buffer, the sensitivity of the
natural area, and the planned recreational use. Hiking and equestrian trails, for example, would be
appropriate in many buffer areas while off-road vehicles would not. While natural habitat not
designated as open space is the preferred buffer, cut slopes, fills, brush management zones, and fuel
breaks may be acceptable depending on the type of habitat.
Some general suggestions for specific habitat types, based on the RPO standards and PSBS
recommendations, are provided below. It is important to keep in mind that these guidelines only
provide minimum buffer sizes, that each case must be evaluated independently, and that there is little
scientific data or even agreement among biologists regarding the appropriate buffer distances in any
given setting.
38
Coastal Sage Scrub and Chaparral
In general, scrub communities such as coastal sage scrub and chaparral should be provided with at
least a 100-foot buffer where interfacing with residences and a 50 to 75-foot buffer where interfacing
with commercial and industrial development, active park uses, and schools. For coastal sage scrub
and chaparral communities occupied by sensitive plants, the buffers are the same as cited above,
because plants are unlikely to be affected by noise and light impacts associated with these types of
developments. The greatest risk to sensitive plants is from trampling by human foot traffic, mountain
bikes, and motorized off-road vehicles. For coastal sage scrub occupied by California gnatcatchers
and other sage scrub avian species, a buffer of at least 200 feet is recommended at interfaces between
residential and commercial development and the occupied habitat. Occupied habitat can be defined
as the native vegetational community that is within the territory of a single pair of birds.
Grasslands
For annual (non-native) and perennial (native) grasslands, buffers of at least 20 to 50 feet are
recommended between the habitat and proposed residential and commercial development. Again,
the precise buffer distance should be determined by the quality and quantity of the specific grassland
habitat. For some annual grasslands, a buffer may be inappropriate or unnecessary under certain
conditions; for instance, where the grassland does not represent sensitive plant or wildlife habitat or
does not serve a corridor function.
Mulefat Scrub
As a component of the riparian system, mulefat scrub should be provided with a buffer that is 50 to
100 feet wide, depending on the quality of the habitat and its function within the matrix of the
surrounding vegetation (e.g., corridor, foraging habitat). The County RPO specifies that 25 feet is
the minimum buffer for riparian habitat; PSBS suggests 100 feet for most interfaces between mulefat
scrub and development.
Southern Willow Scrub/Riparian Habitat
Throughout Southern California, southern willow scrub/riparian woodlands are recognized as highly
productive habitats. The structural diversity of the woodlands and the availability of water and food
resources combine to support a rich diversity and abundance of wildlife species. According to the
County RPO, the "appropriate width of a buffer adjacent to an area of riparian habitat varies
depending upon specific site conditions." The RPO recommends a minimum buffer of 25 feet, but
indicates that buffers up to 200 feet may be required in some instances to maintain the biological
viability of the habitat. To avoid disturbance to resident wildlife, it is recommended that buffers
between riparian woodlands and commercial and residential development be at least 100 feet wide.
Where riparian woodlands are occupied by least Bell's vireo, buffers should be based, to a large
extent, on the width of the riparian corridor. The USFWS, for example, has indicated that the
average width of vireo-occupied habitat on the San Luis Rey River is approximately 800 feet.
Assuming that the 800-foot corridor is appropriate for vireo habitat, buffers should be large enough
to accommodate this width. Hence, if the riparian corridor is 200 feet in width, buffers of at least
300 feet on each side are appropriate (i.e., 300 feet -I- 200 feet + 300 feet = 800 feet). The RPO
suggests 200 feet and PSBS suggests 500 feet as buffers to vireo-inhabited riparian areas.
Oak Woodland
Oak woodlands support considerably more wildlife species than the scrub and grassland communities
discussed above. More than 300 vertebrate species are known to utilize oak-dominated woodlands
39
in California for reproduction, overwintering, and during migration (Block et al. 1990). Human
disturbances to oak woodlands are particularly acute because these woodlands generally are easily
accessed by the public and thus are adversely affected by legitimate recreation activities (i.e., hiking,
mountain bikes, picnicking, etc.) as well as by illegitimate uses (trash dumping, vandalism, itinerant
worker camps, shooting, etc.). Preliminary scientific information concerning urban effects on oak
woodlands adjacent to residential housing indicates a decline in bird species diversity resulting from
the influx of people and human-commensal species such starlings and house sparrows (Scott 1992).
The County RPO sets minimum buffer for oak woodlands at 25 feet from the dripline of an
individual tree or from the edge of an oak woodland. However, to reduce disturbance to wildlife, it
is recommended that buffers between oak woodlands and development be at least 50 to 100 feet
wide. Furthermore, oak woodlands designated as part of a biological preserve either should be off-
limits to the public or receive controlled numbers of visitors engaging in passive recreation activities
(e.g., nature hikes or bird watching restricted to established trails).
4.2.5 OTHER CONSIDERATIONS
In addition to the physical aspects of preserve design, several authors have discussed biological design
criteria, including where preserves ideally should be located, what types of communities and species
they should contain, and how they ultimately should be managed. Biological criteria employed in past
designs for preserves include the diversity, rarity, uniqueness, representativeness of the species,
habitats, and natural communities contained in potential preserve areas (Tubbs and Blackwood 1971;
Goldsmith 1975). Other studies have emphasized that the threat of human interference, availability
of land containing undisturbed natural habitat, and ease of management, also should be considered
in the location of preserves (Tans 1974; Gelbach 1975; Wright 1977). Margules and Usher (1981)
stressed the benefits of using a quantitative scheme to assess the relative suitability of sites for
inclusion in preserve systems. Some of the most successful methodologies have been those that
incorporate information both on the biological value and manageability of natural areas, and outline
procedures for differentially weighting chosen criteria (Duever and Noss 1990).
Fundamental differences between ecosystems necessitate that the physical and biological aspects of
preserve design must be addressed independently for each preserve system. However, results of past
studies provide useful general guidelines, especially with regard to which physical variables are
important for long-term viability of preserves and how biological resources contained in different
potential preserve sites might be compared objectively.
4.3 PRESERVE DESIGN RATIONALE AND APPROACH
A "landscape" approach is used to identify critical biological resource areas in Carlsbad. This
approach, which considers the existing biological diversity within the City, is based upon the following
goals:
• The primary goal is to conserve large landscape-sized features in an interconnected
system of self-sustaining (i.e., independent) ecological units. Although management
will be an important component of the HMP, preserved areas should remain viable
without extreme intervention measures, including extensive vegetative restoration or
translocation of species.
• A secondary goal is to conserve areas known to support viable populations of state
and federally listed endangered and threatened species and their habitats, those
species and habitats likely to become threatened, endangered, or rare in the future,
and other species or habitats of concern on the state, regional, or local level.
40
The methodology used for the biological resource analysis was as follows:
• An attempt was made to broadly categorize areas as to their overall biological value
and sensitivity rather than to plan for a particular subset of species. Because limited
time and money precluded focused, detailed biological surveys throughout the City,
general habitat and vegetation information, specific information from previous
biological surveys (e.g., from EIRs), consultation of resource data bases (e.g., CNDDB
and CNPS), and interviews with local biological experts served as the information base
for identifying the critical resource areas.
• Preserve design criteria and evaluation follow from general conservation principles
and biogeography theory, as discussed above.
4.4 PRESERVE DESIGN METHODOLOGY
The methodology for identifying potential preserve areas and developing a ranking system for
components of the preserve system is described in this section. This approach serves as a guideline
for identifying potential preserve units. The approach was not meant to assign absolute biological
values to each of the units or areas considered for preservation, but to provide relative values for
comparisons among areas. For this reason, while there is a solid scientific foundation for the preserve
design features chosen, the point values assigned in the ranking system were somewhat arbitrary. The
main goal was to develop a ranking system that could be applied objectively and fairly to each of the
areas considered for preservation. This approach represents an amalgamation of approaches used
in other settings (e.g., Duever and Noss 1990; ERCE 1991), but tailored to the needs of the City of
Carlsbad as allowed by the available funds and time to develop the information.
4.4.1 FOCUSED PLANNING AREAS
As an initial step, undeveloped areas within the City of Carlsbad were divided into seven or eight
focused planning areas (FPAs). For purposes of our analyses, "undeveloped areas" were defined in
two alternative ways: (1) all areas that presently are mostly vacant (i.e., without permanent physical
structures) and do not have an approved tentative map (Figure 5); and (2) all areas that presently
are vacant, including those with an approved tentative map (Figure 6). The reason for two different
sets of FPAs is that areas with approved tentative maps may yet be constrained from development
if the California gnatcatcher is federally listed as endangered. Under Section 9 of the federal ESA,
any lands with gnatcatchers would be protected until issuance of a Section 10(a) incidental take
permit or a permit issued pursuant to Section 7 (in the case of a federal action linked to the project).
Lands with gnatcatchers thus would be potential preserve areas even if they had an approved
tentative map. The first alternative (i.e., the pre-gnatcatcher listing scenario) resulted in eight distinct
FPAs. The second alternative (i.e., the post-gnatcatcher listing scenario) resulted in seven distinct
FPAs.
The FPAs were delineated by circumscribing large, continuous areas of the relatively undeveloped
land. Major existing roadways (e.g., El Camino Real and Palomar Airport Road) and existing or
proposed development (under alternative 1) provided relatively natural and intuitive boundaries for
the FPAs.
Using GIS, the entire City of Carlsbad and some adjacent areas in San Marcos and Encinitas were
overlain with a grid comprised of cells 1,000 feet on each side. Each cell contains 22.9 acres. The
grid approach was used because it provides a neutral, objective method for dividing up the focused
planning areas into analyzable units. Public and private property boundaries, proposed land uses, and
circulation elements, which likely will affect the configuration of the preserves, were explicitly
41
NOTE:Focused Planning Areas include
those areas without an approved
tentative tract map and which
are mostly vacant.
SOURCE: SANDAG, April 1992 1" = 6000'
Carlsbad Habitat Management Plan
Pre-Gnatcatcher Listing Focused Planning Areas
NOTE:Focused Planning Areas include
those areas that are presently
vacant and with or without an
approved tentative tract map.
SOURCE: SANDAG, April 1992 1" = 6000'
Carlsbad Habitat Management Plan
Post-Gnatcatcher Listing Focused Planning Areas
excluded from this analysis in order to focus only on biological factors. Also, a grid system is much
more amenable to computer analysis using the GIS data base.
The GIS output from SANDAG was used to generate an overall rating of two features, habitat value
(HV) and habitat sensitivity (HS), utilizing separate layers with vegetation community distributions
and sensitive species. (Vegetation communities and habitat are treated as synonymous here because
each native or introduced community, including introduced eucalyptus, provides habitat for a variety
of species). After each of the cells was rated on HV and HS, they were ranked for their importance
for inclusion in a preserve system. It was assumed that sets of adjacent cells with high rankings would
become the building blocks for the preserve system.
Evaluation of HV was based on: (1) the amount of natural habitat in the cell, including coastal sage
scrub, chaparral, native and non-native grassland, riparian scrub, oak woodland, eucalyptus woodland,
freshwater marsh, salt marsh, disturbed wetland, and open water; (2) the number of different habitats
represented; (3) the connectivity of natural habitats in the cell with habitats of the same type in cells
sharing a side with the focal cell (i.e., excluding cells that connect on the corners); and (4)
vulnerability and manageability, based on land use in the adjacent cells. Each cell was rated for each
feature and given a total HV rating, with a maximum of 100 points.
Evaluation of HS of each cell was based on: (1) the presence and amount of sensitive habitat; (2)
the diversity of sensitive habitats; (3) the presence and abundance of the California gnatcatcher and
coastal sage scrub; (4) numbers of sensitive plant species; and (5) numbers of sensitive wildlife
species. Each cell was rated for each feature and given an HS rating, with a maximum of 100 points.
A separate category for presence of the California gnatcatcher was added because the species is likely
to be federally listed as endangered, and thus will be a key environmental issue for the preserve
system.
4.4.2 PRESERVE FEATURE DEFINITIONS AND RATINGS - HABITAT VALUE
Habitat value refers to the general biological value of each of the cells based upon the presence of
natural vegetation. The presence of sensitive habitats, endangered or threatened species, or other
sensitive biological resources were not considered or given extra weight for the HV rating. The goal
of rating cells for HV simply was to identify those areas that have the best remaining natural
vegetation and habitat in Carlsbad, and those areas that will provide the foundation for a diverse
biological preserve system.
Amount of Natural Vegetation/Habitat Areas
This feature addresses the amount of natural communities or habitat within a cell. The amount of
natural habitat is an important factor for the contribution of a cell to the overall biological viability
of the preserve system. The goal is to assemble several contiguous cells, each with substantial natural
habitat, into a cohesive, self-sustaining ecological preserve area. Also, cells with large amounts of
natural habitat are likely to presently contain more species diversity than cells with less habitat, and
sustain biological diversity (community and species diversity) over long periods of time (Alberts et al.
1992). "Natural communities" encompass coastal sage scrub (all subassociations), chaparral, native
grassland, riparian scrub, disturbed wetland, oak woodland, freshwater marsh, salt marsh, open water,
and non-native associations including eucalyptus woodland and non-native grassland.
42
Criteria and points for amount of habitat were as follows:
Criteria Points
> 22 acres 25
17 to 22 acres 20
11 to 16 acres 15
4 to 10 acres 10
< 4 acres 0
Community/Habitat Diversity
This feature addresses the number of different natural vegetation communities or habitat types within
a cell. The assumption was that cells with several different communities will have relatively more
biological value than cells with little diversity. This assumption, however, is not always correct or
useful. In the case of coastal sage scrub or freshwater marsh, for example, a cell with a single
sensitive community may have extremely high biological value. Such cells were considered on the HS
rating to ensure that they were not undervalued in the final ranking of the cells. For the purpose
of assessing community diversity, the vegetation and habitat types listed above were used. Community
types that have subassociations (e.g., coastal sage scrub and chaparral) were considered as a single
community type. Unfortunately species diversity within a community could not be considered for the
analysis because there are too little current field data. Detailed field investigations would be required
to address species diversity.
Criteria and points for natural community/habitat diversity were as follows:
Criteria Points
> 5 communities 25
4 or 5 communities 20
2 or 3 communities 15
1 community 10
0 natural communities 0
Connectivity of Cell
This feature addresses whether or not a cell has meaningful biological connectivity to adjacent cells.
An adjacent cell was defined as a cell that shares a side with the focal cell. Cells that connect at the
corners of the focal cell were not included in this analysis because the connection is at only a single
point. Thus, each focal cell is adjacent to four other cells. Meaningful biological connectivity was
defined as adjacent cells containing the same community type. For example, if coastal sage scrub
occurs in adjacent cells, those cells are considered to have meaningful biological connectivity because
the species within those cells would comprise a single population, even though the habitat may not
be strictly continuous. Furthermore, the "continuous" habitat could serve as a habitat linkage to
43
other, disjunct cells. The connectivity feature is important for assembling several biologically valuable
units into a cohesive preserve area. The degree or value of connectivity was determined by how
many sides of the focal cell connect with adjacent cells having the same habitat. A cell that connects
to three or four other cells clearly is more valuable as a preserve unit than a cell with only one
connection; i.e., an edge unit (although the edge unit may serve as an effective buffer).
A difficulty that arises with this feature, as defined, is that focal cells bordered by cells with very small
patches of habitat would be given high scores even though the biological "connection" value of the
habitats would be relatively low, particularly with habitats such as coastal sage scrub, chaparral, and
non-native grassland. These habitats must be at least a few acres in size to have much long-term
biological value. Other habitats such as riparian woodland, scrub, marsh habitats, and open water may
have relatively high value even if they comprise only a few acres. To offset the problem of inflated
connectivity scores, adjacent cells had to contain at least one acre of coastal sage scrub, chaparral,
or non-native grassland to be scored as an adjacent cell with the same habitat.
The criteria and points for connectivity were as follows:
Criteria Points
4 sides connecting to same habitat 25
3 sides connecting to same habitat 20
2 sides connecting to same habitat 15
1 side connecting to same habitat 10
0 sides connecting to same habitat 0
Land Uses Adjacent to Cell
This feature addresses whether land uses in adjacent cells are compatible with the biological viability
and integrity of the focal cell. The assumption was that residential, commercial, and industrial
development are existing land uses relatively incompatible with the biological viability of a focal cell
because of the potential for human disturbance, including active recreation (e.g., off-road vehicles
or mountain bikes), predation by pets, trash dumping, and chemical spills. Ultimately edges of the
preserve areas will border adjacent land uses that likely will pose some threat to the preserves.
However, the overall management plan should include measures to minimize adverse impacts on the
preserves by adjacent land uses (e.g., the development of buffers, anti-pet fencing, and deed
restrictions). For the purpose of rating each cell, cells surrounded by natural habitats of any type
received the highest rating, and those surrounded by development or disturbed habitat received the
lowest rating. By definition, an adjacent cell with at least 20 acres of natural habitat was considered
undisturbed.
44
The criteria and points for adjacent land uses were as follows:
Criteria Points
At least 20 acres natural 25
habitat on 4 sides
At least 20 acres natural 20
habitat on 3 sides
At least 20 acres natural 15
habitat on 2 sides
At least 20 acres natural 10
habitat on 1 side
Less than 20 acres natural 0
habitat on any side
4.43 PRESERVE FEATURE DEFINITIONS AND RATINGS -- HABITAT SENSITIVITY
The habitat sensitivity rating considers the presence of sensitive vegetation communities or habitat,
such as coastal sage scrub or wetlands, and the presence, or potential presence based on habitat, of
sensitive wildlife or plants species. Because the proposed endangered California gnatcatcher and
coastal sage scrub is a key issue for development of the HMP, and several other federal candidate
species occupy coastal sage scrub, gnatcatchers and coastal sage scrub were given a separate category.
Amount of Sensitive Habitat
This feature addresses the question of how much, if any, sensitive habitat a cell contains. Sensitive
habitat includes coastal sage scrub (including all subassociations), southern maritime chaparral, oak
woodland, riparian scrub, freshwater marsh, salt marsh, open water, and native grassland.
The criteria and points for amount of sensitive habitat were as follows:
Criteria Points
> 22 acres 20
15 to 22 acres 15
9 to 14 acres 10
2 to 8 acres 5
< 2 acres 0
Five points were added if the cell supports any sensitive habitat other than coastal sage scrub. (This
accounts for the problem that some sensitive habitats often cover small areas, such as wetlands,
riparian woodland, or native grassland.)
45
Diversity of Sensitive Habitats
This feature addresses the diversity of sensitive habitats within a cell. The assumption was that the
greater the diversity of sensitive habitats within a cell, the greater its biological value and the more
valuable it would be for acquisition.
The criteria and points for the diversity of sensitive habitats were as follows:
Criteria Points
4 or more sensitive habitats 20
3 sensitive habitats 15
2 sensitive habitats 10
1 sensitive habitat 5
0 sensitive habitats 0
California Gnatcatcher
This feature addresses the presence of the California gnatcatcher or its habitat within a cell. Because
the gnatcatcher is likely to be federally listed as endangered, preservation of gnatcatcher habitat is
a high priority for the HMP. The highest ratings were given to cells that are known to support
gnatcatchers and have the highest quality gnatcatcher habitat. Areas with coastal sage scrub, but no
documented gnatcatchers received a lower rating.
The criteria and points for gnatcatcher habitat were as follows:
Criteria Points
2 gnatcatcher pairs 20
1 gnatcatcher pair 15
At least 15 acres of coastal 5
sage scrub, but no documented
gnatcatcher pairs
Less than 15 acres of coastal 0
sage scrub or no potential habitat
Sensitive Plants
This feature addresses whether the cell supports plant species that are recognized as sensitive, rare,
or unique by the USFWS, CDFG, CNPS, or other regional or local organizations.
The criteria and points for sensitive plants were as follows:
46
Criteria Points
Documented presence of state or 20
federal endangered or threatened
plant species
Presence of federal candidate 15
species
Presence of two or more CNPS 10
or locally-recognized sensitive
species
Presence of one CNPS or locally- 5
recognized sensitive species
No documented presence of 0
sensitive species
Sensitive Wildlife
This feature addresses the presence of sensitive wildlife, or habitat with potential for supporting
sensitive wildlife, within a cell. Sensitive wildlife was defined as both vertebrates and invertebrates
that have state or federal endangered or threatened status, federal candidate species, state Species
of Special Concern, or species considered sensitive, rare, or unique by regional or local agencies or
organizations. Thus, any sensitive mammals, reptiles, amphibians, birds, or insects were considered
here. Sensitive habitats that provides breeding, foraging, or refuge opportunities for sensitive wildlife
also were considered.
Criteria and points for sensitive wildlife were as follows:
Criteria Points
Documented presence of federal 20
or state endangered or threatened
species
Presence of federal candidate 15
or state Species of Special Concern
Presence of at least 15 acres of 5
sensitive habitat
4.5 RESULTS - HABITAT VALUE
As described in detail above, the analysis of habitat value (HV) for each of the cells was based on
the amount of natural vegetation within a cell, the diversity of vegetation communities, the
connectivity of the cells, and the adjacent land use. For the purpose of analysis, the grid was laid
over a study area consisting of the entire City of Carlsbad and some adjacent areas to the south and
east that contain natural open space (i.e., Encinitas and San Marcos), yielding a total of 1,237 cells
(a total of 28,327 acres). A total of 1,179 cells (26,999 acres) occur either in part or whole in the
Carlsbad City limits. Because the grid was placed in an arbitrary position over the study area, the
47
perimeter cells usually fall partly inside and outside of the City limits. Of the 1,237 cells, 977 cells
(79 percent) scored at least 10 points. This accounts for 22,373 acres of the 28,337 acres in the study
area (see Table 3). Cells scoring no points are located in the most urbanized areas of Carlsbad.
Table 4 shows the frequency distributions for each of the features comprising the HV score. Each
of the features is discussed below.
4.5.1 AMOUNT OF NATURAL HABITAT
The frequency distribution for the amount feature illustrated in Table 4 demonstrates that the values
for the feature are well distributed. There were 336 cells (34 percent) receiving scores of 20 or
better (i.e., cells with 17 acres or more). There were 480 cells (49 percent) receiving scores of 10 or
less (i.e., 10 or fewer acres).
4.5.2 HABITAT DIVERSITY
For the diversity of vegetation communities, the scores for cells also were well distributed. However,
the scores tended to fall more in the middle values than with the amount feature. Only five cells
received scores of 25 (> 5 different communities) while only 11 cells received scores of 0 (no natural
communities). However, 134 cells received scores of 20 or better (4 or more different communities).
TABLE 4
FREQUENCY DISTRIBUTION FOR HABITAT VALUE FEATURES
Habitat Value Features
Assigned
Value
0
10
15
20
25
Amount
244*
236
162
180
156
Diversity
11
302
531
129
5
Connectivity
73
50
147
264
444
Adjacent
Land Use
450
272
165
62
29
TOTAL 978 978 978 978
The number or frequency of cells assigned a particular value
48
4.5.3 HABITAT CONNECTIVITY
Cells tended to fall at the high end of values for the connectivity feature; 444 cells (45 percent)
received scores of 25. The reason for this result is because the threshold for inclusion as a connected
adjacent cell was fairly liberal. If a cell had any habitat that was the same as the focal cell, except
for coastal sage scrub, chaparral, or non-native grassland, it was scored as a connected adjacent cell.
This liberal criterion was used because even very small patches of certain vegetation communities,
such as riparian woodland, salt and freshwater marsh, or native grassland, have high biological value
and are valuable if proximate to the same habitat in an adjacent cell. For coastal sage scrub,
chaparral, and non-native grassland, the threshold for scoring as an adjacent cell was that it must
contain at least one acre of the same vegetation community. The rationale for this contingency is
that these communities require somewhat larger areas to provide viable habitat for wildlife and plant
species. The one acre requirement thus eliminates slivers of extremely small patches of vegetation
that carry relatively little biological value.
4.5.4 ADJACENT LAND USE
Adjacent land use scores provided almost a mirror image of the distribution for connectivity; 722 cells
(74 percent) scored 0 or 10 and only 256 cells (26 percent) scored 15 or more. In other words,
relatively few cells have adjacent cells with 20 or more acres on at least two sides.
4.5.5 COMPOSITE HABITAT VALUE
Table 5 shows the composite HV frequency distribution. This distribution reflects the total score of
each of the cells achieved by adding the scores for each of the HV features discussed above. No cells
had a perfect score of 100. The overall distribution approximates a normal (bell-shaped) distribution,
with most of the scores falling in the middle of the distribution. There were, however, a
disproportionate number of scores, assuming a normal distribution, with a score of only 10. These
cells are located in the more urbanized areas of Carlsbad and tend not to occur in the FPAs. Overall,
228 cells (23 percent) scored 75 points or better, 382 cells (39 percent) scored 50 to 70 points, 269
cells (27 percent) scored 25 to 45 points, and 98 cells (10 percent) scored 20 points or fewer.
The spatial distribution of HV scores is illustrated in Figure 7. The map illustrates that cells with the
highest scores tend to cluster together. Clustering here is defined as a focal cell having a direct
connection with another cell either by sharing a side or connecting on a corner. Only four of the 228
cells scoring 75 points or more were not in some way directly connected (including a connection on
a corner) to an adjacent cell scoring at least 75 points. In part, this is because connectivity was a
factor in the HV score, but it also reflects the fact that Carlsbad still has relatively large, contiguous
areas with high habitat value. Approximately 5,100 acres of the best habitat in Carlsbad generally
occurs together. These clusters range in size from about 850 acres in the southeast part of the City
to about 68 acres in the northern part. Cells that received scores between 50 and 70 tend to
surround the highest scoring clusters. Cells with lower scores tend to be around the perimeter of the
higher scoring clusters and in the areas outside of the FPAs. Only five of 96 cells scoring 20 points
or fewer are completely surrounded by cells scoring at least 25 points.
Figure 7 shows that the FPAs do indeed capture most of the best remaining habitat in Carlsbad.
49
Points
B75 +
50-74 4-
Q25 - 49
DO - 24
SOURCE: SANDAG, August 1992
Approx. Scale:
1" = 5900'
Carlsbad Habitat Management Plan
Habitat Value Map
TABLE 5
COMPOSITE HABITAT VALUE
Value Frequency Value Frequency
10
15
20
25
30
35
40
45
50
57
7
34
44
59
40
67
59
77
55
60
65
70
75
80
85
90
95
84
77
70
74
80
63
53
28
4
TOTAL 977
4.6 DISCUSSION -- HABITAT VALUE
Decisions concerning habitat acquisition and implementation of the preserve and corridor system will
in large part rest on the habitat value of the parcels considered for acquisition, as well as upon
acquirability, economic, and land use factors. Any strategy, however, will allow for acquisition of only
a portion of the remaining natural habitat within the City. The optimum strategy is to acquire and
conserve the best remaining core areas and link them by multiple habitat corridors.
The results of the HV analysis indicate that Carlsbad should have reasonably good flexibility in
establishing an interconnected preserve system, because there are six or seven core areas with
generally high habitat value. Some subset of three or four of these areas, with corridor linkages
connecting all or part of the system, would be desirable. Most important, it appears that Carlsbad
at least has the raw biological material from which to assemble a functional preserve system.
While an analysis of general HV is an important aspect of delineating potential preserve areas,
information about general species richness and the presence of sensitive habitat and species also is
important. The HV analysis provides a starting point from which to consider the other factors
important for designing feasible and functional preserves. The next section considers the presence
and distribution of sensitive habitat and species.
4.7 RESULTS -- HABITAT SENSITIVITY
The analysis of habitat sensitivity (HS) for each cell was based on the amount of sensitive habitat(s)
within the cell, the presence of, or habitat for, the California gnatcatcher, the presence of sensitive
plants, and the presence of sensitive wildlife species. Sensitive habitats included coastal sage scrub
(including all subassociations), southern maritime chaparral, oak woodland, riparian scrub, freshwater
marsh, salt marsh, open water, and native grassland.
50
4.7.1 AMOUNT OF SENSITIVE HABITAT
The frequency distribution for the amount of sensitive habitat within a cell is well distributed (Table
6). Most cells scored relatively low, but 268 cells (27 percent) received 15 or 20 points. These 23-
acre cells contain at least 15 acres of sensitive habitat. This kind of distribution was expected because
sensitive habitats, by definition, are more rare and comprise fewer total acres than other habitats.
This is especially true for riparian, marsh, and native grassland habitats.
4.7.2 SENSITIVE HABITAT DIVERSITY
The frequency distribution for the diversity of sensitive habitats is similar to that for the amount of
sensitive habitat. Most cells received a low score, but 129 cells (13 percent) received 15 or 20 points.
That is, these cells contain three or more different sensitive habitats within the same cell.
TABLE 6
FREQUENCY DISTRIBUTION FOR HABITAT SENSITIVITY FEATURES
Habitat Sensitivity Features
Assigned
Value
0
5
10
15
20
Size
267
218
225
133
135
Diversity
164
457
228
%
33
Gnatcatcher
Presence
833
65
NA
66
14
Sensitive
Plants
820
105
34
9
10
Sensitive
Wildlife
742
150
NA
5
81
TOTAL 978 978 978 978 978
4.7.3 CALIFORNIA GNATCATCHER
Table 6 and Figure 4 show the most recent publicly available information concerning the distribution
of California gnatcatchers in the City of Carlsbad. (It is important to note that all not all areas of
the City have been surveyed for gnatcatchers nor were all data available for public review at the time
of this writing.) Cells scoring 20 points had two gnatcatcher pairs, cells scoring 15 points had one
pair, and cells scoring 5 points had no documented pairs, but contained at least 15 acres of coastal
sage scrub, and thus have at least some potential to support gnatcatchers. Figure 4 illustrates that
the gnatcatcher distribution tends to cluster similarly to cells scoring high in habitat value (see Figure
51
7), with the exception of 17 pairs in disjunct or isolated cells (i.e., cells having no direct connection
with another cell either containing gnatcatchers or having at least 15 acres of coastal sage scrub).
4.7.4 SENSITIVE PLANTS
Table 6 shows the distribution of cells containing plants with three levels of sensitivity: state or
federally threatened or endangered, federal candidates, and CNPS or locally-recognized sensitive
species. Only 10 cells contained plants with the most sensitive status and only nine cells contained
federal candidate species. Plants with CNPS or local status were found in 139 cells.
4.7.5 SENSITIVE WILDLIFE
The California gnatcatcher is a proposed endangered species. However, because it is likely to be
listed as endangered by early 1993, it was treated in the analysis as federally endangered. The
gnatcatcher was also included under sensitive wildlife, in addition to its own category, because of its
high profile in the HMP process. In essence, it receives more than double weighting in this analysis
because any cells containing a single gnatcatcher pair receives 20 points. Table 6 shows that 81 cells
received 20 points; 80 of which contain gnatcatchers and one of which contains a least Bell's vireo.
Only five cells contain federal candidate species, including the San Diego horned lizard and orange-
throated whiptail (see Figure 4). Because the data base for sensitive wildlife is primarily comprised
of biological surveys conducted for EIRs, there is a paucity of information on sensitive wildlife
compared to the amount of information available on the presence of sensitive habitats and
gnatcatchers. The absence of other sensitive species from cells may only reflect a lack of focused
surveys for these species. Prior to acquisition of habitat for the preserves, additional focused surveys
for sensitive wildlife will be necessary if this factor is to be an important acquisition criterion.
4.7.6 COMPOSITE HABITAT SENSITIVITY
Table 7 shows the composite frequency distribution for HS resulting from adding the feature scores
for each cell. The scores are well distributed, but skewed toward the lower scores. This was expected
due to the rarity and uniqueness of the biological resources considered sensitive. Only eight cells (< 1
percent) scored 75 points or more, 74 cells (7 percent) scored 50 to 70 points, 284 cells (29 percent)
scored 25 to 45 points, and 612 cells (62 percent) scored 20 points or fewer.
Cells with higher HS scores tend to be clustered in the FPAs (Figure 8). Only 14 of 82 cells (17
percent) that scored more than 50 points are completely isolated from other cells scoring at least 50
points. Twelve cells scoring at least 50 points are connected only at the corner with another cell
scoring at least 50 points. In other words, of the 82 cells scoring at least 50 points, 56 (68 percent)
share at least a side with another cell scoring 50 or more points. As would be expected, the
distribution of cells with high HS scores generally matches the distribution of cells with high HV
scores. However, because the HS score represents more rare and unique biological resources, the
absolute scores for HS are generally lower than HV scores on a cell by cell comparison. Only two
cells that scored at least 75 on HS scored lower than 75 on HV.
52
Points
875 +
50-74 +-
Q25 - 49
DO - 24
I
SOURCE: SANDAG, August 1992
Approx. Scale:
1" = 5900'
Carlsbad Habitat Management Plan
Habitat Sensitivity Map
Value
TABLE 7
COMPOSITE HABITAT SENSITIVITY
Frequency Value Frequency
0
5
10
15
20
25
30
35
40
143
108
164
95
102
68
76
70
44
45
50
55
60
65
70
75
75
80
85
26
19
19
17
9
10
3
3
3
2
TOTAL 978
4.8 HABITAT SENSITIVITY - DISCUSSION
As with overall HV, the distribution of cells with high HS scores generally are concentrated in the
FPAs. An acquisition strategy that focuses on cells with high HV usually will include the cells that
have high HS scores. However, some relatively isolated cells receiving high HS scores may be worth
acquiring, because they contain resources, such as a sensitive plant, that can be protected with only
a small amount of habitat. Consequently, those cells with high HS scores should be evaluated
individually to determine whether they should be acquired.
4.9 TOTAL HABITAT VALUE/SENSITIVITY -- RESULTS
For each cell, the HV and HS scores were summed to yield a total HV/HS score (Table 8). Only 13
cells (1 percent) scored at least 150 points, 257 cells (26 percent) scored 100 to 145 points, 456 cells
(47 percent) scored 50 to 95 points, and 252 cells (26 percent) scored less than 50 points. Cells that
scored at least 100 points account for approximately 6,183 acres of the approximately 10,000 acres
of natural habitat remaining in the City of Carlsbad.
As with HV and HS considered separately, cells with high total HV/HS scores are clustered in the
FPAs (Figure 9). Only six cells within the City boundaries scoring at least 100 points are completely
isolated from other cells scoring at least 100 points. Only seven cells scoring at least 100 points are
connected only at a diagonal to another cell scoring at least 100 points. All other cells scoring at
least 100 points connect on at least one full side with another cell scoring at least as well.
53
Points
150 +
100 - 149
Q50 - 99
DO - 49
SOURCE: SANDAG, August 1992
Approx. Scale:
1" = 5900'
Carlsbad Habitat Management Plan
Total Habitat Value/Sensitivity Map
TABLES
TOTAL HABITAT VALUE/SENSITIVITY FREQUENCY DISTRIBUTION
Value Frequency Value
TOTAL
Frequency
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
27
30
17
14
34
37
52
41
53
50
46
44
47
43
41
49
90
95
100
105
110
115
120
125
130
135
140
145
150
155
160
165
170
46
37
38
40
36
36
29
29
24
10
7
8
3
3
3
2
2
978
4.10 TOTAL HABITAT VALUE/SENSITIVITY - DISCUSSION
The results for the total HV/HS were similar to the results for HV and HS considered separately.
For this reason, further analyses of the FPAs will focus on the total HV/HS scores. These scores will
also be used to determine potential wildlife corridors to link the core preserve areas.
The results suggest that the City of Carlsbad has several areas with high biological value and hence
high potential value as part of a preserve system. Fortunately, as illustrated in Figure 9, these areas
tend to cluster in the FPAs, and thus are at least potentially available for acquisition. Because these
biologically valuable areas comprise more than 6,000 acres, it is clear that only a subset of the areas
with high HS/HV will be acquired for the preserves.
From a purely biological perspective, the preserve lands acquisition strategy should include at least
three components:
• Clustered cells scoring at least 100 points should receive top priority in the preserve system.
• Cells scoring 50 to 100 points that share a side with higher scoring cells also should be
considered for inclusion in the core preserves, but with a lower priority. These cells may
serve as buffers for the higher quality habitat and as potential corridors.
54
• As cells are considered for acquisition, potential habitat linkages between core areas should
be considered.
4.11 LIMITATIONS OF APPROACH
The preserve design approach taken here has some limitations. It has been noted that the sensitive
species data base is not complete because not all areas of the City of Carlsbad have been surveyed.
Also, the number of sensitive species not recognized by the resource agencies has grown considerably
in the past few years and, thus, species considered to be sensitive now were not necessarily surveyed
for in past efforts. Therefore, even for sites with good biological information, surveys for sensitive
species may have been inadequate. From the perspective of sensitive species alone, a more complete
data base may result in some modifications to the existing preserve planning areas in order to
encompass sensitive species that were not captured in this phase of the work. Work conducted in
Phase III of the HMP and beyond will in part be directed to developing a more complete sensitive
species data base from ongoing and future field work.
55
SECI ON i
Preserve Recommendations
BIOLOGICAL RESOURCES AND HABITAT ANALYSIS
in support of the CITY OF CARLSBAD HABITAT MANAGEMENT PLAN
SECTION 5
PRESERVE RECOMMENDATIONS
5.1 INTRODUCTION
In this section, recommendations intended to assist the City of Carlsbad in assembling a viable
biological preserve system are provided. This section consists of an analysis of the proposed core
preserve areas from which the ultimate preserve system will be built, identification of potential
wildlife corridors that would serve to link the core areas, and an analysis of potential land uses
adjacent to preserve areas in terms of their impacts and ways to minimize those impacts.
The goal of this section is to provide the City of Carlsbad with the information necessary to
implement a preserve land acquisition strategy. As such, specific minimal preserve boundaries are
not drawn. Rather, the analysis will allow the City to choose from a menu of alternative preserve
options that will result in a viable preserve system in concert with concurrent conservation efforts in
the region (e.g., the North County MHCP, the Clean Water Program MSCP, and the County of San
Diego OSHMP). In this way, the City will have the maximum flexibility in implementing the preserve
system.
5.1.1 SIZE OF PRESERVE SYSTEM
An important issue for the establishment of preserves is determining the sizes of the individual core
preserves and the overall system. The solution to this depends on several factors, including the area
needed to support minimum viable populations of the key species included in the preserves, the
quality of the habitat preserved, connections between core preserve areas, adjacent land uses, and
long-term management of the preserve system. As discussed in Section 4.2, the larger the preserves,
the better, because species' extinction rates are inversely related to patch size (Diamond 1975; Wright
and Hubbell 1983; Usher 1987; Soule 1991). Soule et al. (1988) suggest that habitat fragments in
southern California smaller than 250 ha (617 acres) will likely lose some species. All things being
equal, smaller preserves require a greater level of protection and more intense, hands-on management
to remain viable (Noss 1983).
Unfortunately, the fundamental biological information needed to specify the minimum areas required
by key species is lacking. For this reason, the City of Carlsbad should take a conservative approach
to identifying the areas targeted for acquisition and retain as much flexibility as possible in
implementing the HMP. As biological information on key species (e.g., the California gnatcatcher
and orange-throated whiptail) accrues, the preserve system should be fine-tuned to meet the needs
of these species and maintain functional ecological systems.
5.2 POTENTIAL CORE PRESERVE AREAS
In Section 4.4.1, pre- and post-gnatcatcher focused planning areas (FPAs) were described. The FPAs
included undeveloped areas in the City of Carlsbad that have relatively contiguous natural habitat.
It was clear that the biological preserve system would be developed from some subset of the FPAs
because the best remaining habitat in Carlsbad is captured in the FPAs and much of the habitat likely
would be available for acquisition. However, the amount of natural habitat in the FPAs was far more
than would be feasible to acquire for the final preserve system. Upon completion of the habitat value
(HV) and habitat sensitivity (HS) analyses, it was possible to further refine the FPAs. The results
of this analysis yielded a set of preserve planning areas. The preserve planning areas are
56
distinguished from the FPAs in terms of the quality of habitat included. The methodology and results
of this analysis are presented below.
5.2.1 METHODS
In order to refine the FPAs, a simple decision rule about whether to include a specific habitat cell
in the preserve planning area was employed1. Any habitat cell scoring fewer than 100 points that
was not adjacent to another habitat cell scoring at least 100 points was excluded from the preserve
planning area. Adjacency was defined as the habitat cell sharing at least one side with a cell scoring
at least 100 points; i.e., connections at corners with cells scoring at least 100 points did not qualify
a cell for inclusion in the preserve planning area. Cells scoring fewer than 100 points were included
in the preserve planning area if adjacent on at least one side to a high scoring cell because they may
serve as corridors between better habitat or as buffers.
It is important to note that this method was used only to circumscribe potential core preserve areas
and was not intended to identify wildlife corridors. The methodology to identify corridors is described
below. It also is important to note that the circumscribed areas provide an artificial picture of the
ultimate preserve areas, because the grid overlay was placed in an arbitrary position. The final
preserve areas likely will have boundaries that follow the contours of property boundaries, vegetation,
topography, and other constraints or open space plans included in development projects. The
circumscribed areas described here as potential core preserve areas provide a guide to the best
remaining natural habitat in Carlsbad rather than a specific delineation of where precise boundaries
should fall.
5.2.2 RESULTS
Separate analyses were carried out for the pre- and post-gnatcatcher listing FPAs (see Figures 5 and
6). Figures 10 and 11 show the pre-listing and post-listing preserve planning areas, respectively.
Figure 10 shows the vegetation communities occurring in the pre-listing preserve planning areas.
Table 9 provides the acreages by aggregated vegetation type for the pre-listing preserve planning
areas. Figure 11 shows the vegetation communities occurring in the post-listing preserve planning
areas. Table 10 provides the acreages by aggregated vegetation type for the post-gnatcatcher listing
preserve planning areas.
Within the pre- and post-California gnatcatcher listing preserve planning areas, the following
percentages of native vegetation types within the City are included in the total preserve planning
area:
Pre Post
Coastal Sage Scrub 65% 77%
Chaparral 58% 73%
Native Grassland 23% 27%
Saltwater/Freshwater Marsh 48% 78%
1 The preserve planning areas discussed here were determined prior to minor final revisions of
the vegetation map. A few cells along the boundaries of the preserve planning areas changed value
in the final run of the habitat value/sensitivity analysis and would not have been included in the
preserve planning areas. Changes to the preserve planning areas as a result of the vegetation
revisions will be considered in Phase III of the HMP.
57
TABLE 9
ACREAGES BY AGGREGATED VEGETATION TYPES
PRE-CALIFORNIA GNATCATCHER LISTING
PRESERVE PLANNING AREAS
Vegetation/Land Cover
Within
PPAs PPA 1
Pre Listing Acreages
PPA 2 PPA 3 PPA 4 PPAS PPA 6 PPA 7
Not
Within
PPAs
Coastal Sage Scrub
Diegan Coastal Sage Scrub
Maritime Succulent Scrub
Disturbed Coastal Sage Scrub,
Maritime Succulent Scrub
Chaparral
Southern Mixed Chaparral
Chamise Chaparral
Southern Maritime Chaparral
Coastal Sage/Chaparral Mix
Disturbed Chaparral, Southern
Maritime Chaparral, Coastal
Sage/Chaparral Mix
Native Grassland
Non-Native Grassland
Disturbed Grassland
1,684
350
1,142
0
10
0
0
465
85
564
80
128
32
66 214
21 77
174 167
0
3 856
0 29
0 205
0
819
283
838
40
5
941
0
113
0
123
0
37
2
145
4
446
0
0
0
78
17
1,507
58
TABLE 9
(Continued)
Vegetation/Land Cover
Saltwater Marsh
Freshwater Marsh
Riparian Scrub
Oak Woodland
Sycamore Alluvial Woodland
Eucalyptus Woodland
Open Water
Disturbed Wetland
Disturbed Habitat, Active,
Agriculture, Golf Course
Developed
TOTAL WITHIN PPAs
TOTAL BY PPA
TOTAL FOR CITY
Pre Listing Acreages
Within
PPAs PPA 1 PPA 2 PPA 3 PPA 4 PPA 5 PPA 6 PPA 7
173 8 16 33 08 107 0
249 58 70 26 3 54 17 21
124 0 108 0 96 02
61 0 4 0 5 8 33 12
1,026 108 223 264 0 7 422 2
88 40 2 6 3 35 00
1,233 35 381 222 165 291 47 93
293 21 72 30 84 20 42 24
7,378
393 2,113 859 679 1,341 671 1,322
24,940
Not
Within
PPAs
186
219
27
241
77
102
3,311
9,898
17,563
Source: SANDAG, 7/92
59
TABLE 10
ACREAGES BY AGGREGATED VEGETATION TYPES
POST-CALIFORNIA GNATCATCHER LISTING
PRESERVE PLANNING AREAS
Vegetation/Land Cover
Within
PPAs PPA 1
Pre Listing Acreages
PPA 2 PPA 3 PPA 4 PPAS PPA 6 PPA 7
Not
Within
PPAs
Coastal Sage Scrub
Diegan Coastal Sage Scrub
Maritime Succulent Scrub
Disturbed Coastal Sage Scrub,
Maritime Succulent Scrub
Chaparral
Southern Mixed Chaparral
Chamise Chaparral
Southern Maritime Chaparral
Coastal Sage/Chaparral Mix
Disturbed Chaparral, Southern
Maritime Chaparral, Coastal
Sage/Chaparral Mix
Native Grassland
Non-Native Grassland
Disturbed Grassland
1,955
469
1,439
35
0
10
0
588
91
582
0
125
228
190
130 214
24 77
194 167
0
3 8%
0 39
0 306
0 27
548
164
540
13
6
1,562
0
113
0
159
0
189
3
177
4
446
0
0
0
478
16
887
60
TABLE 10
(Continued)
Vegetation/Land Cover
Saltwater Marsh
Freshwater Marsh
Riparian Scrub
Oak Woodland
Sycamore Alluvial Woodland
Eucalyptus Woodland
Open Water
Disturbed Wetland
Disturbed Habitat, Active,
Agriculture, Golf Course
Developed
TOTAL WITHIN PPAs
TOTAL BY PPA
TOTAL FOR CITY
Within
PPAs PPA 1
278 8
354 58
136 0
102 0
1,062 108
124 40
1,466 35
408 21
9,396
393
24,940
Pre Listing Acreages
PPA 2 PPA 3 PPA 4 PPAS PPA 6 PPA 7
16 137 0 8 107 1
83 87 5 54 17 51
119 0 96 03
5 28 11 8 33 17
258 265 0 7 422 2
2 42 4 35 00
447 341 190 291 47 167
95 76 105 20 42 48
2,446 1,708 854 1,341 671 1,983
Not
Within
PPAs
80
114
15
200
41
66
3,078
9,783
15,544
Source: SANDAG, 7/92
61
Pre Post
Riparian Scrub 53% 76%
Oak/Sycamore Alluvial Woodland 82% 90%
Open Water 97% 96%
With the exception of native grassland, and salt and freshwater marsh under the pre-listing scenario,
the majority of native habitat within the City is included in the preserve planning areas. Salt and
freshwater marsh, however, already have statutory protection.
The preserve planning area analysis allows for the designation of those areas in Carlsbad that
constitute the best remaining habitat within the City. The fact that the City retains more than 7,300
acres of good habitat under the pre-gnatcatcher listing alternative and nearly 9,400 acres under the
post-gnatcatcher listing alternative indicates that the City has an excellent opportunity to assemble
a biological preserve system. Each preserve planning area is considered in detail below.
Sensitive Species
Figure 4 shows the distribution of sensitive species in the City of Carlsbad and Section 2 provides a
detailed discussion of each species. Information concerning sensitive species was gathered from
existing EIRs, other environmental documents, and discussions with local experts. Tables 11 and 12
provide a matrix of records for sensitive species by preserve planning area for both the pre- and post-
listing scenarios, respectively.
Under the pre-listing scenario, preserve planning areas 2, 4, 5, and 7 contain a good diversity of both
sensitive wildlife and plant species. Under the post-listing scenario, the results are similar, with the
exception that preserve planning area 3 captures much greater diversity, because its area is greatly
expanded, from 859 acres to 1,708 acres.
Tables 11 and 12 list all the sensitive species recorded from the preserve planning areas based on
information available for the present study. There certainly are more instances of sensitive species
occurring in these areas than presented here. For example, the Belding's Savannah sparrow likely
is much more widespread in the salt marsh habitat around the lagoons than reflected in these data.
Not all of the sensitive wildlife and plant species occurring in Carlsbad are captured in the preserve
planning areas. These omissions may reflect gaps in the ultimate protection of these areas. On the
other hand, existing protected lands or designated open space may provide protection for some of
these resources. Resolution of such questions requires performance of a "gap analysis", which will
be performed in Phase III of the HMP work plan.
62
TABLE 11
PRE-CALIFORNIA GNATCATCHER LISTING
PRESERVE PLANNING AREA SENSITIVE SPECIES RECORDS
Preserve Planning Area3
Species 123456 7
WILDLIFE
Belding's Savannah Sparrow
California Gnatcatcher l& 2 6 13 35
California Least Tern
Least Bell's Vireo
Light-footed Clapper Rail
Orange-throated Whiptail 3 2
San Diego Horned Lizard 2
PLANTS
Ashy-spike Moss X° XX X
California Adolphia X XX
Del Mar Manzanita X X
Engelmann Oak X X
Orcutt's Brodiaea
San Diego Golden-star X
San Diego Thorn-mint
Spiny Rush XX X
Summer-holly X XX
Wart-stemmed Ceanothus X X
Western Dichondra X X
a Based on existing available data. New surveys were not performed in potential PPAs
b Indicates number of records
c Indicates presence
63
TABLE 12
POST-CALIFORNIA GNATCATCHER LISTING
PRESERVE PLANNING AREA SENSITIVE SPECIES RECORDS
Preserve Planning Area
Species 123456 7
WILDLIFE
Belding's Savannah Sparrow 1
California Gnatcatcher 16 6 7 13 40
California Least Tern 1
Least Bell's Vireo 1
Light-footed Clapper Rail 1
Orange-throated Whiptail 3 2
San Diego Horned Lizard 2
PLANTS
Ashy-spike Moss
California Adolphia
Del Mar Manzanita
Engelmann Oak
Orcutt's Brodiaea
San Diego Golden-star
San Diego Thorn-mint
Spiny Rush
Summer-holly
Wart-stemmed Ceanothus
Western Dichondra
X
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sensitive species known to occur outside of the pre-listing preserve planning areas include:
Belding's Savannah Sparrow
Light-footed Clapper Rail
California Least Tern
Least Bell's Vireo
Chocolate Lily
Cliff Spurge
Del Mar Mesa Sand Aster
San Diego Marsh Elder
Thread-leaved Brodiaea
The post-listing preserve planning areas capture more sensitive species, because they are larger.
However, sensitive species known to occur outside of the post-listing preserve planning areas include:
64
Chocolate Lily
Cliff Spurge
Del Mar Mesa Sand Aster
San Diego Marsh Elder
Thread-leaved Brodiaea
Fortunately, most of the species not captured by the preserve planning areas are plants that could
be preserved by acquiring small areas of land or implementing some type of localized protection
program (conservation easements, fencing, etc.).
Based on available information and discussions with local experts, it is estimated that there are
between 113 and 166 California gnatcatcher pairs in the City of Carlsbad (P. Mock, pers. comm.).
The 113 known to the City probably underestimate the total, because some coastal sage scrub habitat
is unsurveyed. Of the known gnatcatchers in the City, the pre-listing preserve planning area includes
approximately 72 pairs and the post-listing preserve planning area includes approximately 82 pairs.
The remaining known pairs tend to be scattered among fragments of coastal sage scrub habitat
throughout the City. Some of these pairs inhabit areas already protected as open space or along
utility easements. Thus, most of the known gnatcatchers subject to the greatest risk are included in
the preserve planning areas. These gnatcatchers also tend to be clustered wherever they occur.
Therefore Carlsbad will have the opportunity to make a significant contribution to the conservation
of gnatcatchers on a regional basis.
Each of the preserve planning areas are discussed in detail below.
Pre-Gnatcatcher Listing Preserve Planning Areas
Preserve Planning Area 1 (PPA1)
PPA1 consists primarily of the Buena Vista Lagoon in its western portion and Buena Vista Creek
in its eastern portion. This 393-acre area lies at the northwestern border of Carlsbad, and is bounded
by State Highway 78 on the north and urban development on the south. The dominant habitat type
is the open water of the lagoon (108 acres). The eastern portion supports riparian scrub and non-
native annual grassland. The planning area also includes some small patches of disturbed habitat.
As a potential preserve area, PPA1 contains highly sensitive wetland habitats. The lagoons and salt
marsh and freshwater marsh habitats are statutorily protected from development under Section 404
of the federal Clean Water Act and Section 1600 of the California Fish and Game Code.
Furthermore, Buena Vista Lagoon is managed as an ecological reserve area by CDFG and is
therefore already under state protection and management.
The open water habitat of the lagoon supports a variety of fishes and provides foraging habitat for
numerous waterfowl, diving birds, and shorebirds. Sensitive wildlife species likely to occur in the
lagoon or the associated salt marsh include the Belding's Savannah sparrow, light-footed clapper rail,
California least tern, and salt-marsh skipper. Freshwater marsh provides habitat for two sensitive
plant species: spiny rush and San Diego marsh elder.
Carlsbad will need to manage the watershed and tidal influences that affect the viability of the lagoon,
as well as Batiquitos and Agua Hedionda lagoons. While the lagoons and marsh habitat currently
have statutory protection, and thus do not require acquisition, the HMP should include provisions
for preserving or enhancing the quality of these valuable resources. A concern recently voiced is the
enforcement of runoff control measures to reduce sedimentation into the lagoons, and in particular
65
Batiquitos. Another concern is to manage the watersheds of the lagoons to ensure a balance between
freshwater and tidal influences on the fragile lagoon ecosystem.
Preserve Planning Area 2 (PPA2)
PPA2 contains 2,113 acres generally located east of Tamarack Avenue, northeast of El Camino Real,
and north of Palomar Airport Road. The dominant vegetation in this area is coastal sage scrub and
chaparral (1,114 acres), with relatively large patches of disturbed habitat interspersed with the sage
scrub and chaparral. This area supports one of the two remaining areas in Carlsbad with large,
contiguous stands of coastal sage scrub. Other notable features in PPA2 include Lake Calavera and
Squires Dam, riparian scrub, and well developed oak woodlands in the southern portion of the area.
The important habitat in PPA2 occurs in three large blocks: around Lake Calavera, the block of
coastal sage scrub east of Rancho Carlsbad Golf Course, and the block of coastal sage scrub and
chaparral around Agua Hedionda Creek in the southeast portion of the planning area. The northern
and southern portions contain the greatest diversity and density of sensitive species. These areas
should be the focus of future acquisitions. Ideally, these sub-areas would be acquired as large habitat
blocks connected by wildlife corridors. The woodland along Agua Hedionda Creek would provide
a potential connection between the more southern habitat blocks.
PPA2 supports substantial coastal sage scrub (550 acres) and the second greatest concentration of
gnatcatchers in the City, as well as several other sensitive species (Table 12). Portions of PPA2 will
serve as a key part of the preserve system .
Preserve Planning Area 3 (PPA3)
PPA3 is an 859-acre area primarily comprised of Agua Hedionda Lagoon (264 acres) in the west
portion. The area lies south of Tamarack Avenue, north of Palomar Airport Road, and is bisected
by Hidden Valley Road. The eastern portion of PPA3 supports riparian scrub and relatively small
areas of coastal sage scrub in the eastern portion. The greatest value of PPA3 is the lagoon and
riparian scrub, because these areas already have statutory protection. The remaining habitat in PPA3
is marginal: the patches of coastal sage scrub and chaparral would become fragmented with eventual
development to the north and northeast (e.g., Evans Point) and thus will not connect with other scrub
or chaparral in the City available for acquisition under the pre-listing scenario.
Preserve Planning Area 4 (PPA4)
PPA4 is a 679-acre area bordered on the north by Palomar Airport Road, on the east by El Camino
Real, and on the north and south by development. This area contains patches of maritime succulent
scrub in the western portion, chaparral in the central and eastern portion, and some smaller areas of
riparian scrub and oak woodland. Much of PPA4 supports non-native grassland and disturbed habitat
(310 acres). The coastal sage scrub in PPA4 borders relatively large stands of sage scrub to the north
and south, but these areas are rapidly urbanizing. It is unlikely that the coastal sage scrub remaining
in this area will retain high biological value over the years unless adjacent development projects
include preservation of substantial areas of coastal sage scrub. The chaparral in the central and
eastern portion of PPA4 is intact and connects to some large patches of chaparral to the east in
PPA5. The chaparral-oak woodland mosaic in the eastern part of the area is the best habitat in
PPA4.
The primary value of PPA4 is that it contains a variety of sensitive plants associated with maritime
succulent scrub. Fortunately these patches of habitat can be preserved without requiring acquisition
of large areas or connections to other habitat, since the primary purpose will be to preserve sensitive
vegetation.
66
Preserve Planning Area 5 (PPA5)
PPA5 contains 1,341 acres. The area is bounded on the north by Palomar Airport Road, on the
south by Alga Road, on the west by El Camino Real, and on the west by the City of San Marcos.
PPA5 supports a patchwork of coastal sage scrub, chaparral, oak woodland, and riparian scrub. The
dominant vegetation, however, is non-native grassland (446 acres). The coastal sage scrub and
chaparral habitats in PPA5 are much more fragmented than the habitats in PPA2 or PPA7.
However, the coastal sage scrub on the eastern boundary of PPA5 connects with substantial coastal
sage scrub in the City of San Marcos.
Despite the apparent fragmentation of habitat in PPA5, this planning area supports at least 13
gnatcatcher pairs and a variety of sensitive plants (Table 12). PPA5 also would serve an important
function as a link between the coastal sage scrub and chaparral habitats in PPA2 and PPA7.
Potential corridors exist along the western edge of the area, just to the east of the western edge, and
in the eastern part of PPA5. The habitat along the western edge, which parallels El Camino Real,
consists primarily of chaparral and does not connect to other large chaparral patches. The more
interior corridor is comprised of discrete but proximate patches of coastal sage scrub and riparian
scrub. This potential corridor may function for coastal sage scrub species such as the gnatcatcher.
The eastern corridor would require the assemblage of small fragmented patches of coastal sage scrub
and riparian habitat to serve as a conduit for coastal sage scrub species. The most promising habitat
link lies to the east and would connect with coastal sage scrub habitat in San Marcos (see discussion
of wildlife corridors below).
Preserve Planning Area 6 (PPA6)
PPA6 consists of the Batiquitos Lagoon area and comprises 671 acres. This area is bordered on the
south by La Costa Avenue and the City of Encinitas, on the east by El Camino Real, and on the
north by residential development and disturbed habitat. PPA6 is dominated by the open water
habitat of the lagoon, with salt and freshwater marsh along the edges (529 total acres). As described
above for the Buena Vista Lagoon, biologically this habitat is extremely valuable and sensitive.
Sensitive species likely to occur also are as described above. The CDFG manages the Batiquitos
Lagoon as an ecological preserve, and thus it is already under state protection.
Preserve Planning Area 7 (PPA7)
PPA7 consists of a 1,322-acre area located in the southeastern portion of the City. The property
primarily is owned by the Fieldstone Company. This area is bisected by Rancho Santa Fe Road,
bordered on the north by Alga Road, and on the southeast by the City of Encinitas. PPA7 supports
the largest contiguous stand of coastal sage scrub in the City of Carlsbad and currently provides
habitat for at least 35 gnatcatcher pairs. The remaining habitat in the PPA7 mostly is comprised of
chaparral (205 acres) with smaller patches of non-native grassland and disturbed habitat in the central
portion. There also are small areas of riparian scrub and a small area of open water.
In addition to gnatcatchers, PPA7 supports a variety of sensitive plants. PPA7 will be a significant
part of the preserve system because of its coastal sage scrub habitat. In coordination with the
USFWS and the City of Carlsbad, the Fieldstone Company has a pre-listing Habitat Conservation
Plan (HCP) proposal for preservation of nearly 500 acres of coastal sage scrub and gnatcatcher
habitat as mitigation for their residential development project and the widening of Rancho Santa Fe
Road. This preserved habitat will be a keystone of the City's preserve system and will provide a link
to other gnatcatcher populations and coastal sage scrub in the City of Carlsbad, as well as with coastal
sage scrub habitat outside of the City. This regional linkage will be essential for the viability of the
67
Carlsbad gnatcatcher population and will contribute to the viability of the regional gnatcatcher
population.
Post-Gnatcatcher Listing Preserve Planning Areas
The post-listing preserve planning areas are larger than the pre-listing areas because they include
undeveloped areas that have an approved tentative map. However, there is a great degree of
concordance between the two sets of planning areas. In this section, significant differences in the
preserve planning areas are noted.
Preserve Planning Area 1 (PPA1)
Same as pre-listing PPA1.
Preserve Planning Area 2 (PPA2)
PPA2 generally is the same as the pre-listing PPA2. The post-listing PPA2 contains 2,446 acres
generally located east of Tamarack Avenue, northeast of El Camino Real, and north of Palomar
Airport Road. The dominant vegetation in this area is coastal sage scrub and chaparral (1,261 acres),
with relatively large patches of disturbed habitat interspersed with the sage scrub and chaparral. The
post-listing scenario differs from the pre-listing scenario primarily in the addition of a large area of
coastal sage scrub in the northern portion. While addition of this area increases the amount of
coastal sage scrub in PPA2, there are no records of gnatcatchers in the added habitat. This area
does, however, support a substantial population of California adolphia.
Preserve Planning Area 3 (PPA3)
The post-listing PPA3 extends the planning area well to the north and south of the pre-listing
planning area. PPA3 contains 1,708 acres including the Agua Hedionda Lagoon, marsh habitat, a
mosaic of coastal sage scrub, chaparral, non-native grassland, and disturbed habitat in the northern
portion. The value of the post-listing PPA3 is significantly improved over the pre-listing planning area
via the addition of substantial sage scrub and chaparral. The number of sensitive wildlife and plant
species captured greatly increases by the expansion of PPA3 (Table 12). Also, the expanded area
creates more opportunities for connecting the adjacent preserve planning areas.
Preserve Planning Area 4 (PPA4)
The post-listing PPA4, at 854 acres, is somewhat larger than the pre-listing PPA4, with the addition
of some coastal sage scrub and non-native grassland in the northwest corner and some chaparral and
eucalyptus stands in the southern part. However, much of the habitat in PPA4 is non-native
grassland and disturbed habitat. With the additional habitat in the north, PPA4 could serve as a link
between PPA3 and PPA6. As described above, the primary value of PPA4 is the large number of
sensitive plants that occur in the area.
Preserve Planning Area 5 (PPA5)
The post-listing PPA5 is the same as the pre-listing PPA5.
Preserve Planning Area 6 (PPA6)
The post-listing PPA6 is the same as the pre-listing PPA6.
68
Preserve Planning Area 7 (PPA7)
The post-listing PPA7 encompasses the pre-listing PPA7 and adds habitat in the extreme southeast
corner of the City for a total of 1,983 acres. As described above, PPA7 includes the largest single
area of continuous coastal sage scrub in the Carlsbad. The areas to the south add some areas of
chaparral, coastal sage scrub, and riparian scrub, but the additional area mostly supports non-native
grassland. However, the number of known gnatcatchers in PPA7 is 40 and the number of sensitive
plants increases as well (Table 12). The addition of these areas also provides the potential for linking
PPA6 (Batiquitos Lagoon) and PPA7 via riparian scrub habitat.
5.3 POTENTIAL WILDLIFE CORRIDORS
As discussed in Section 4.2.3, the degree of isolation of individual preserves is an important design
consideration, because one of the functions of a preserve system is to promote regional biological
diversity. For maintenance of biodiversity, it is assumed that at least modest levels of migration
between preserves via habitat linkages or wildlife corridors must occur to prevent local extinctions
within the individual preserves. Some of the key factors for wildlife corridors to function effectively
are: (1) isolated preserves must be as close together as possible to facilitate exchange of individuals
between subpopulations (Diamond 1975; Wilson and Willis 1975); (2) corridors must be wide enough
to overcome edge effects; (3) corridors must possess appropriate habitat and cover for the key species
expected to travel through them; and (4) corridors must have as few turns or other barriers to
movement as feasible (Soule and Gilpin 1991).
5.3.1 METHODS
Potential wildlife corridors linking the preserve planning areas in Carlsbad were identified by
examining the vegetation map with the pre- and post-listing planning area overlays (see Figures 10
and 11). Those areas identified as possible corridors provide either the shortest physical link between
two preserve planning areas or areas with continuous or nearly continuous habitat that wildlife could
use for movement and cover. In several cases, the corridors cross major roadways such as El Camino
Real or Palomar Airport Road, because there is no other way of connecting preserve areas. In these
cases, the habitat of the planning areas generally abuts the road. These kinds of corridors will be of
limited value, however, because they would preclude use by certain species.
Not all of the corridors identified will be functional or desirable. In some cases, a corridor may
effectively link two areas, but be non-functional because the two preserves support different species.
Such a corridor could even be detrimental in the long term because animals using it may be at greater
risk to predation resulting from edge effects, relative lack of cover or refuge, and unfamiliarity with
the area. The corridor, in essence, acts as a "sink" for individuals and serves to reduce numbers in
the feeder populations.
The dashed lines signifying wildlife corridors in Figures 10 and 11 represent strips 375 feet wide.
Ideally, corridors should be at least 1,000 feet wide to provide adequate cover and space for the
wildlife. However, the minimum width will depend on the type of habitat, the length of the corridor,
and the amount of cover provided. (See discussion of buffers and distance setbacks provided in
Section 4.2.4.)
It is important to keep in mind that the corridors discussed below refer only to potential connections
between preserve planning areas. Because the preserve planning areas represent the best remaining
contiguous natural habitat in the City, the proposed corridors almost always will consist of more
degraded or fragmented habitat. Also, as the preserve planning areas are further refined, corridors
within the preserve planning areas will become important (i.e., local or internal corridors). The same
69
principles discussed below for the corridors will apply to the local corridors. Fortunately, because
these corridors would be developed in habitat considered of high biological value, it should be easier
to design connections that contain appropriate habitat and adequate space.
5.3.2 RESULTS
Pre-Gnatcatcher Listing Wildlife Corridors
Figure 10 illustrates the potential wildlife corridors under the pre-listing scenario. For brevity, the
wildlife corridors are coded by the preserve planning areas they connect. For example, the wildlife
corridor between PPA1 and PPA2 is coded as WC1-2. Where there are multiple corridors connecting
two preserves, a capital letter is added to the code to distinguish the different connections.
WC1-2 is approximately 2,000 feet in length and crosses patches of coastal sage scrub. The value of
this corridor is questionable because it connects the coastal sage scrub in PPA2 with non-native
grassland in PPA1, and thus would not serve a useful function for coastal sage scrub species. This
is an example of a wildlife corridor that could function as a sink for some species. Larger mammals,
such as coyotes, foxes, skunks or raccoons probably would use this corridor.
WC2-5A bridges a gap of approximately 2,600 feet between chaparral north of Palomar Airport Road
in PPA2 and chaparral to the south in PPA5. The corridor crosses Palomar Airport Road and
disturbed habitat. The major impediment posed along this corridor is the roadway. Palomar Airport
Road receives heavy traffic flow during the day, which would preclude diurnal movements of wildlife.
Species capable of moving at night, such as coyotes, foxes, raccoons, skunks, and perhaps bobcats,
may be able to cross the roadway without great risk. Rabbits and rodents also may effectively use
this corridor.
WC2-5B connects PPA2 and PPA5 via strips of coastal sage scrub and disturbed habitat approximately
3,700 feet long and about 700 feet wide. It ties in oak woodland in PPA2 with a patch of coastal
sage scrub in PPA5. This corridor could function for larger species as well as small coastal sage scrub
species. The major obstacle in this corridor is Palomar Airport Road, which may inhibit or preclude
movement by some species as described for WC2-5A
WC4-5 connects the east part of PPA4 with the west part of PPA5. This corridor would connect
patches of chaparral in the two preserve planning areas and may link areas of oak woodland in the
two preserve areas. The major drawback to this linkage is that it crosses El Camino Real, which
poses an obstacle to smaller and diurnal species. Larger nocturnal species likely use this corridor
without much difficulty. As discussed above, however, the main biological value of PPA4 comes from
sensitive plants species. The wildlife in PPA4 is threatened by urbanization to the north. Therefore,
a wildlife corridor linking PPA4 and PPA5 probably is of low priority.
WC4-6 connects the southern portion of PPA4 with the northern portion of PPA6 at Batiquitos
Lagoon. The corridor crosses Alga Road and extends approximately 5,000 feet through disturbed and
eucalyptus woodland habitat. Because of the lack of cover and the obstacle posed by Alga Road, use
of the corridor would be limited to crepuscular and nocturnal movements by species such as skunks,
foxes, raccoons, coyotes, and perhaps bobcats. The eucalyptus woodland provides habitat for raptors
and other birds.
WC5-7A is located east of the City boundary and connects PPA5 with PPA7. It extends
approximately 6,000 feet, of which 4,500 feet is coastal sage scrub, 1,100 feet is riparian scrub, and
400 feet is developed. This may be a critical link between the coastal sage scrub habitat and coastal
sage scrub species in the southeast portion of Carlsbad and that in the City of San Marcos.
70
WC5-7B is a 3,300-foot corridor approximately 300-400 feet wide that connects PPA5 and PPA7. It
follows an existing powerline easement. The corridor primarily supports non-native grassland and
probably serves as a corridor for larger species such as coyotes, foxes, and skunks. It would not be
particularly useful for coastal sage scrub species because there is relatively little scrub habitat in
PPA5. Small species that use non-native grasslands, such as rodents and rabbits could use this
corridor as well.
WC5-6,7 comprises La Costa Golf Course. It connects PPA5 and PPA7 and links with PPA6 via a
strip of marsh and disturbed habitat. While golf courses do not serve as corridors for many sage scrub
and chaparral species, larger mammalian species such as coyotes and rabbits will use such areas for
movements. The connection to PPA6 would provide a corridor for species using Batiquitos Lagoon.
Post-Gnatcatcher Listing Wildlife Corridors
WC1-2 is the same as the pre-listing WCl-2.
WC2-3A is a 3,700-foot corridor that connects PPA2 and PPA3. This corridor includes coastal sage
scrub, non-native annual grassland, and disturbed habitat. It links coastal sage scrub habitat in PPA2
with riparian scrub, eucalyptus woodland, and disturbed habitat in PPA3. There are areas of
chaparral and coastal sage scrub in the northern part of PPA3 that potentially could link with PPA2
habitat via this corridor. The drawback to this corridor is that it crosses El Camino Real below the
intersection of El Camino and Tamarack Avenue, thus precluding or inhibiting the movement of
diurnal and smaller species that would have difficulty safely crossing a four-lane thoroughfare.
WC2-3B is a 4,500-foot corridor that connects PPA2 and PPA3 just to the east of WC2-3A via
riparian scrub. This corridor, although lengthy, directly connects coastal sage scrub in PPA2 with
riparian scrub on PPA3. Again, however, the corridor must cross El Camino Real, thus providing an
obstacle to the movement of many animals. The other main disadvantage of this corridor is that it
is rather narrow ~ generally less than 200 feet wide and is adjacent to disturbed habitat.
WC2-3C is a 1,500-foot corridor that connects riparian scrub in PPA2 with eucalyptus woodland in
PPA3. A patch of chaparral lies southwest of the eucalyptus. This may be an effective corridor for
some avian species that can use the riparian scrub and oak woodland to the east in PPA2 and also
utilize the eucalyptus woodland and riparian habitats in PPA3. As with the other corridors
connecting PPA2 and PPA3, El Camino Real provides an obstacle to movement between the two
areas, although it would not be an obstacle to many avian species.
WC2-5A is the same as the pre-listing WC2-5A.
WC2-5B is the same as the pre-listing WC2-5B.
WC3-4 is a 500-foot corridor between PPA3 and PPA4. This corridor probably would not serve an
important function because it is interrupted by Palomar Airport Road. Also, the western end of
PPA4 has questionable value as a wildlife preserve because is consists of a patchwork of coastal sage
scrub, non-native grassland, and disturbed habitat.
WC4-5 is the same as the pre-listing WC4-5.
WC4-6 is the same as the pre-listing WC4-6.
WC5-7A is the same as the pre-listing WC5-7A.
71
WC5-7B is the same as the pre-listing WC5-7B.
WC5-6,7 is the same as the pre-listing WCS-6,7.
WC6-7 is a 3,000-foot corridor that connects the eastern end of PPA6 and the western end of PPA7.
The corridor supports riparian scrub that is 500-700 feet wide. This corridor would serve to connect
marsh areas in PPA6 with riparian scrub in PPA7. An obstacle for this corridor is the La Costa
Avenue-El Camino Real intersection area. This corridor likely would be effective for avian species
that use the marsh/riparian habitats, but limited for small mammals.
WC7-7A is an 1,100-foot corridor that connects two parts of PPA7. The corridor supports non-native
grassland and connects non-native grassland areas in the two parts of PPA7. There also are some
patches of coastal sage scrub, riparian scrub, and chaparral near the corridor connection that
potentially could benefit from the linkage.
W7-7B is a 1,500-foot corridor that connects two parts of PPA7. The corridor contains disturbed
habitat and non-native grassland.
5.4 CONCEPTUAL PRESERVE SYSTEM
Under the City of Carlsbad Draft Comprehensive Open Space and Conservation Resource
Management Plan, dated January 3, 1992, three existing preserves are present within the City:
Batiquitos Lagoon, Buena Vista Lagoon, and the University of California Reserve. The recent
conservation proposal between the City, Fieldstone, and the USFWS concerning gnatcatchers and
coastal sage scrub would establish a fourth preserve of nearly 500 acres in the vicinity of Rancho
Santa Fe Road. Assuming that the lagoons and associated marsh/wetland habitat, riparian scrub and
woodland habitat, and the Fieldstone site have protected status, approximately 2,500 acres of habitat
in the City is protected. This does not include areas already under City protection provided by
General Plan and zoning controls, such as hillsides, steep slopes, canyons, or areas identified as part
of the City trails system. Those protected lands still must be added to the information base to
identify valuable, yet unprotected, lands.
The intent of this report is to provide the City of Carlsbad with the requisite biological information
to supplement the natural resources already under protection in the City. As such, the information
provided in the form of the rated habitat cells, preserve planning areas, and potential wildlife
corridors should provide the City with the basic information needed to guide future resource
planning.
It is recommended that the City consider acquisition of at least two or three additional habitat areas
to develop a complete preserve system. The best remaining habitat areas in the City are located
around the western end of Lake Calavera and the riparian scrub running south from the lake, the
Agua Hedionda Creek area south of Squires Dam, the western portion of PPA5, and the central
portion of PPA4. Ideally, the Lake Calavera, Agua Hedionda Creek, and PPA5 areas could be linked
with wildlife corridors. Local corridors within PPA2 have not been specifically identified. The
corridor between PPA2 and PPA5 is WC2-5A. PPA5 and PPA7 could be linked with WC5-7B. As
described above, the central portion of PPA4 supports maritime succulent scrub and a variety of
sensitive plant species. These areas could be preserved effectively without additional wildlife
corridors.
It is important to note that these recommendations are very general. It is not possible at this time
to specify parcels for acquisition. Several steps are necessary before the City can begin acquiring
habitat for the preserve system, including:
72
• Identification of habitat areas already under public ownership or part of the Citywide
trails system (i.e., the gap analysis)
• Identification of habitat areas protected as open space in existing and proposed
development projects
• Analysis of how public and protected habitat relates to unprotected core preserve
areas identified in this document
• Targeting of specific acquisition areas based upon the above analyses
• Focused biological field surveys of targeted areas to validate the habitat analysis
presented here and to provide current information on general and sensitive resource
diversity and abundance
5.5 COMPATIBLE LAND USE ANALYSIS
One of the difficult challenges for designing and implementing a preserve system in the City of
Carlsbad will be to specify appropriate buffers and setbacks between development and preserve areas,
as well as to define acceptable human uses of preserve areas. A discussion of buffers and setbacks
is presented in Section 4, along with some recommendations relating to different habitat types. These
recommendations are based on guidelines from the San Diego County RPO and a separate set of
guidelines from PSBS.
There are very little data on the impacts of development on preserve areas. One point of general
agreement, however, is that buffers and setbacks should not be considered as part of the preserve
area. These areas will certainly be degraded by human related activity. Researchers presently are
conducting studies on the "natural/urban interface" and some guidelines should be forthcoming in the
next few years (e.g., Scott 1992; Savaujot 1992).
In the absence of quantitative data on impacts by development, there are a few general guidelines
that should be followed in delineating preserve boundaries. These guidelines relate to the physical
features of the landscape and planned uses in developed areas.
With regard to physical features, vegetation and topography can play an important role in how well
a natural area is protected by affecting the level of public access to a natural area. In the absence
of an established trail system, dense vegetation (e.g., chaparral, coastal sage scrub, or wetland habitat)
can provide barriers to access by both humans and pets. Likewise, a preserve boundary on a ridgeline
surrounded by steep slopes can restrict access to the preserved area. In natural areas used by the
public, low wooden fencing or planting of shrub species, such as ceanothus or cactus, can serve to
limit trespass into sensitive areas. That is, most people choose the path of least resistance, and few
are likely to make the effort to gain access to rugged or densely vegetated areas. Recreation
activities such as hiking, jogging, walking dogs, and mountain biking should be limited to specified
trails and rigorously enforced. These activities, however, may not be appropriate for some preserved
areas. The general idea is to create a preserve system where easy public access is restricted either
by natural or artificial physical features. Such a benign approach (as opposed to wire fencing, heavy
patrol, etc.) is preferable because of the cost savings and the public's perception of the resource as
available for public enjoyment.
Development adjacent to preserve areas poses varying degrees of risk to them. Medium and high
density residential development probably poses the greatest risk, because of the sheer number of
people, noise, lighting, use of nearby open space for recreation, pets, human-commensal species (e.g.,
73
starlings and house sparrows that compete with native species for nesting areas and other resources),
arson and accidental fires, and trash dumping. Preserve areas near residential developments will
require the greatest amount of buffering either through distance, vegetation, topography, or fencing.
Commercial development poses less of a risk to natural open space because of the limited time
people use these areas, the absence of children, and the absence of pets. The most compatible land
uses include active recreation areas such as parks, athletic fields (although nighttime lighting may be
a problem), golf courses, and active agricultural uses. The greatest risk posed by these uses would
be maintenance operations, such as the use of chemicals on maintained turf or crops. Also, control
of runoff from cultivated areas is an important issue.
A final, and very difficult issue, is that of itinerant worker camps scattered throughout the drainages
and canyons of Carlsbad. These camps are located in some of the most sensitive habitats in the City
(e.g., oak woodlands and riparian areas or any areas with heavy canopy cover and an open
understory). The presence of the camps has seriously degraded these habitats because of trash and
garbage, trampling of vegetation, and unsanitary living conditions (e.g., open latrine areas).
Ultimately, the City will have to address this problem if these sensitive areas are to be preserved.
Also, many of the areas used by the itinerant workers constitute important wildlife corridors and
habitat linkages. The presence of people in these areas certainly disrupts their use by wildlife.
5.6 CONCLUSION
The City of Carlsbad has the opportunity to develop a preserve system to conserve a variety of
general and sensitive biological resources. This analysis provides the biological information necessary
for implementing a preserve system within the City that will integrate with regional conservation
planning efforts. It is anticipated that the City can effectively develop a preserve system using the
information provided in this document, along with additional information regarding land use and
public and private property ownership in the City. This document is a fundamental step toward
achieving that goal.
74
SECI ON
Acknowledgements
X
BIOLOGICAL RESOURCES AND HABITAT ANALYSIS
in support of the CITY OF CARLSBAD HABITAT MANAGEMENT PLAN
SECTION 6
ACKNOWLEDGEMENTS
Completion of the Biological Resources Inventory and Analysis phase of the Carlsbad Habitat
Management Plan was the joint effort of many participants. The HMP Advisory Committee is to be
commended for their faithful attendance and participation at the monthly meetings. Rick Alexander
of Consultants Collaborative, Inc. provided excellent leadership and guidance in his role as chair of
the committee. Don Rideout and Michael Holzmiller of the City of Carlsbad were critical to the
success of the work through their provision of City resources. Bob Parrott, Paula Cunningham, and
Sue Carnevale of SANDAG provided GIS services, and Bob wrote the computer program for the
habitat quality analyses. Also important to the success of this project were numerous property owners
and their consultants who provided additional information and corrections to the biological resources
data base. Finally, we thank the many reviewers who provided valuable comments on the draft
document.
The following are the biological consultant team members:
H. Lee Jones, Ph.D. - Project Director, Michael Brandman Associates
Allison Alberts, Ph.D. -- Preserve Design Specialist, Center for the Reproduction of Endangered
Species, Zoological Society of San Diego
Philip R. Behrends, Ph.D. -- Project Manager, Biologist, Dudek & Associates
Nancy Bell-Gallagher -- Graphic Artist, Michael Brandman Associates
John W. Brown, Ph.D. -- Biologist, Dudek & Associates
Martie A. demons -- Graphic Artist, Dudek & Associates
Michael Evans -- Natural Resources Consultant
Sarah A. Flick -- Botanist, Michael Brandman Associates
Tonette S. Foster -- Word Processing, Administrative Assistant, Dudek & Associates
Marcia McRae -- Word Processing, Administrative Assistant, Michael Brandman Associates
Gregory Pregill, Ph.D. -- Sensitive Amphibians and Reptiles, San Diego Natural History Museum
Fran Saveriano - Regional Business Manager, Michael Brandman Associates
Wayne D. Spencer, Ph.D. -- Biologist, Michael Brandman Associates
Fred T. Sproul -- Sensitive Plant Species, Plant Ecology
Harold (Howie) Wier - Biologist, Dudek & Associates
75
SECT ON 7
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SECTION 7
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81
FEDERAL AND STATE DESIGNATED
SENSITIVE PLANT AND WILDLIFE
SPECIES RESIDENT OR BREEDING IN
SAN DIEGO COUNTY
BIOLOGICAL RESOURCES AND HABITAT ANALYSIS
in support of the ClTY OF CARLSBAD HABITAT MANAGEMENT PLAN
FEDERAL AND STATE DESIGNATED SENSITIVE WILDLIFE SPECIES
OCCURRING IN SAN DIEGO COUNTY
SPECIES USFWS CDFG
BIRDS
Aimophila ruficeps canescens C23
Southern California Rufous-crowned Sparrow
Agelaius tricolor
Tricolored Blackbird
C2
None
CSC?
Ammodramus (Passerculus) sandwichensis beldingi
Belding's Savannah Sparrow
Ammodramus (Passerculus) sandwichensis rostratus
Large-Billed Savannah Sparrow
Amphispiza bellii bellii
Bell's Sage Sparrow
Campylorhynchus brunneicapillus sandiegensis
Coastal Cactus Wren
Charadrius alexandrinus nivosus
Western Snowy Plover
Chilodanius niger
Black Tern
C2
C2
C2
C2
Cld
C2
CSC
None
None
CSC
None
Empidonax traillii extimus
Southwestern Willow Flycatcher
Eremophila alpestris actia
California Horned Lark
Falco peregrinus anatum
American Peregine Falcon
Haliaeetus leucocephalus
Bald Eagle
Lanius ludovicianus
Loggerhead Shrike
Laterallus jamaicensis
Black Rail
Cl
C2
FEf
FE
C2
C2
None
None
SE
SE
None
None
Oreortyx pictus
Moutan Quail
Pelecanus occidentalis califomicus
California Brown Pelican
Plegadis chihi
White-faced Ibis
Polioptila californica californica
California Gnatcatcher
Rallus longirostris levipes
Light-footed Clapper Rail
Sterna antillarum browni
California Least Tern
Sterna elegans
Elegant Tern
Strix occidentalis occidentalis
California Spotted Owl
Vireo bellii pusillus
Least Bell's Vireo
C2
FE
C2
Proposed
Endangered
FE
FE
C2
C2
FE
None
SE
CSC
CSC
SE
SE
CSC
None
SE
MAMMALS
Choeronycteris mexicana
Mexican Long-tongued Bat
Dipodomys stephensi
Stephens' Kangaroo Rat
Euderma maculatum
Spotted Bat
Eumops perotis califomicus
California Mastiff Bat
Lepus califomicus bennettii
San Diego Black-tailed Jackrabbit
Macrotus califomicus
California Leaf-nosed Bat
Neotoma lepida intermedia
San Diego Desert Woodrat
C2
FE
C2
C2
C2
C2
C2
None
STf
None
CSC
None
CSC
None
Onychomys torridus ramona C2
Southern Grasshopper Mouse
Ovis canadensis cremnobates C2
Pennisular Bighorn Sheep
Perognathus (Chaetodipus) califomicus femoralis C2
Dulzura California Pocket Mouse
Perognathus (Chaetodipus) fallax fallax C2
Northwestern San Diego Pocket Mouse
None
ST
None
None
Perognathus (Chaetodipus) fallax pallidus
Pallid San Diego Pocket Mouse
Perognathus longimembris brevinasus
Los Angeles Pocket Mouse
Perognathus longimembris intemationalis
Jucumba Little Pocket Mouse
Perognathus longimembris pacificus
Pacific Pocket Mouse
C2
C2
C2
C2
None
CSC
None
CSC
REPTILES
Ambystoma califomiense
California Tiger Salamander
Cnemidophorus hyperythrus
Orange-throated Whiptail
Cnemidophorus tigris multiscutatus
Coastal Western Whiptail
Clemmys mamarota pallida
Southwestern Pond Turtle
Coleonyx swaitafd
Barefoot Banded Gecko
Coleonyx variegatus abbotti
San Diego Banded Gecko
Crotalus ruber ruber
Northern Red Diamond Rattlesnake
C2
C2
C2
Cl
C2
C2
C2
None
CSC
None
CSC
ST
None
None
Diadophus punctatus similis
San Diego Ringneck Snake
Eumeces skiltonianus interparietalis
Coronado Skink
Lampropeltis zonata pulchra
San Diego Mountain Kingsnake
Licharana trivirigata rosafusca
Coastal Rosy Boa
Phrynosoma coronatum blainvillei
San Diego Horned Lizard
Phrynosoma mcalli
Flat-tailed Horned Lizard
Salvadora hexalepis virgultea
Western Patch-nosed Snake
Sauromalus obesus
Common Chuckwalla
Sceloporus graciosus vandenburgianus
Southern Sagebrush Lizard
Thamnophis hammondi
Two-striped Garter Snake
C2
C2
C2
C2
C2
Cl
C2
C2
C2
C2
None
None
None
None
CSC
CSC
None
None
None
None
AMPHIBIANS
Bufo (microscaphus califomicus) califomicus
Arroyo Toad
Ensatina eschscholtzi klauberi
Large-blotched Salamander
Rana aurora draytoni
California Red-legged Frog
Rana muscosa
C2
C2
Cl
C2
CSC
CSC
CSC
CSC
Mountain Yellow-legged Frog
INVERTEBRATES
INSECTA
Coelus globosus
Globose Dune Beetle
Euphydryas editha quino
Quino Checker
Euphyes viestris harbonsi
Harbison's Dun Skipper
Lycaena hermes
Herme Copper
Mitoura thornei
Thome's Hairstreak
Panoquina errans
Salt Marsh Skipper
Pseudocopaeodes eunus
Wandering Skipper
Pyragus ruralis lagunae
Laguna Mountains Skipper
C2
C2
C2
C2
C2
C2
C2
C2
None
None
None
None
None
None
None
None
ANOSTRACA
Branchinecta "sandiegonensis
San Diego Fairy Shrimp
Streptocephalus woottoni
Riverside Fairy Shrimp
Petitioned for
Listing as Endangered
Proposed None
Endangered
C2 - Category 2 Candidate*
CSC — California Species of Special Concern
SE -- State Endangered
Cl — Category 1 Candidate'
FE — Federally Endangered
ST — State Threatened
Species currently imdescribed, but under consideration for species status.
Category 2 Candidate for federal listing includes those taxa for which existing
biological information may warrant listing, but for which substantial biological
information to support a proposed listing is lacking.
Category 1 Candidate for federal listing includes those taxa for which there exists
sufficient biological information to support a proposal to list as threatened or
endangered.
STATE AND FEDERALLY RECOGNIZED SENSITIVE PLANT
SPECIES OCCURRING IN SAN DIEGO COUNTY
SPECIES USFWS CDFG CNPS*
Acanthomintha Uicifolia
San Diego Thorn-mint
Ambrosia pumila
San Diego Ambrosia
Aphanisma blitoides
Aphanisma
Arctostaphylos otayensis
Otay Manzanita
Astragalus deanei
Dean's Milk Vetch
Astragalus douglasii var. perstrictus
Jacumba Milk Vetch
Astragalus magdalenae var. peirsonii
Peirson's Milk Vetch
Astragalus oocarpus
Descanso Milk Vetch
Astragalus tener var. titi
Coastal Dunes Milk Vetch
Baccharis vanessae
Encinitas Baccharis
Brodiaea filifolia
Thread-leaved Brodiaea
Brodiaea orcuttii
Orcutt's Brodiaea
Calamagrostis densa
Dense Reed Grass
Calamintha (Satureia) chandleri
Cl
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
SE
None
None
None
None
None
SE
None
SE
SE
SE
None
None
None
List IB, 3-3-2
List IB, 3-2-2
List 3, ?-?-2
List IB, 3-2-3
List IB, 3-2-3
List IB, 1-2-2
List IB, 2-2-2
List IB, 3-1-3
List IB, 3-3-3
List IB, 2-3-3
List IB, 3-3-3
List IB, 1-3-2
List 4, 1-1-2
List 4, 1-1-2
San Miguel Savory
Calochortus dunnu Cl
Dunn's Mariposa Lily
Caulanthus simulans Cl
Payson's Caulanthus
Caulanthus stenocarpus Cl
Slender-pod Caulanthus
Ceanothus cyaneus Cl
Lakeside Ceanothus (wild-lilac)
Chaenactis parishii C2
Parish's Chaenactis
Chorizanthe orcuttiana Cl
Orcutt's Spineflower
Chorizanthe parryi var. femandina Cl
San Fernando Valley Spineflower
Cordylanthus maritimus ssp. maritimus FE
Salt Marsh Bird's-beak
Corethrogyne filaginifolia var. linifolia Cl
Del Mar Mesa Sand Aster
Cryptantha ganderi Cl
Gander's Cryptantha
Delphinium hesperium ssp. cuyamacae Cl
Cuyamaca Larkspur
Downingia concolorvar. brevior Cl
Cuyamaca Lake Downingia
Dudleya brevifolia Cl
Short-leaved Dudleya
Dudleya multicaulis Cl
Many-stemmed Dudleya
Dudleya variegata Cl
Variegated Dudleya
Dudleya viscida Cl
Sticky Dudleya
Eryngium aristulatum var. parishii Cl
San Diego Button-celery
Rare List IB, 2-2-2
None List 4, 1-2-3
Rare List IB, 3-2-2
None List IB, 3-2-2
None List 4, 1-1-2
SE List 1A
None List 1A
SE List IB, 2-2-2
None List IB, 3-2-3
None List IB, 3-3-3
Rare List Ib, 2-2-3
SE List IB, 3-3-3
SE List IB, 3-3-3
None List IB, 1-2-3
None List 4, 1-2-2
None List IB, 3-2-3
SE List IB, 1-3-2
Ferocactus acanthodes C2
California Barrel Cactus
Ferocactus viridescens C2
San Diego Barrel Cactus
Fremontodendron mexicanum C2
Mexican Flannelbush
Galium angustifolium ssp. borregoense C2
Borrego Bedstraw
Githopsis diffusa ssp. filicaulis C2
Mission Canyon Bluecup
Hazardia orcuttii C2
Orcutt's Hazardia
Hemizonia conjugens C2
Otay Tarplant
Hemizonia floribunda C2
Tecate Tarplant
Heuchera brevistaminea C2
Laguna Mtns. Alumroot
Lepechinia cardiophylla C2
Heart-leaved Pitcher Sage
Lepechinia ganderi C2
Gander's Pitcher-sage
Lepidium flavwn var. felipense C2
Borrego Peppergrass
Lessingia glandulifera var. tomentosa C2
Warner Springs Lessingia
Lilium parryi var. parryi C2
Lemon Lily
Limnanthes gracilis var. parishii C2
Parish's Meadowfoam
Linanthus orcuttii C2
Orcutt's Linanthus
Lupinus excubitus var. medius C2
Mountain Springs Bush Lupine
None List 4, 7-3-2
None List 2, 1-3-1
Rare List IB, 3-2-2
Rare List IB, 3-2-3
None List IB, 3-3-2
None List IB, 3-3-2
SE List IB, 3-3-2
None List IB, 2-2-2
None List IB, 3-1-3
None List IB, 3-1-2
None List IB, 3-1-2
None List IB, 3-1-3
None List IB, 3-1-3
None List 4, 1-2-2
SE List IB, 2-2-3
None List IB, 3-1-2
None List IB, 2-1-3
Machaeranthera asteroides var. lagunensis C2
Laguna Mtns. Aster
Mahonia nevinii Cl
Nevin's Barberry
Mimulus aridus C2
Low Bush Monkey Rower
Monardella hypoleuca var. lanata C2
Felt-leaved Monardella
Monardella linoides spp. viminea
Willowy Monardella
Monardella nana ssp. leptosiphon
San Felipe Monardella
Mullla clevelandii
San Diego Goldenstar
Myosurus minimus var. apus
Little Mousetail
Navarretia fossalis
San Diego (Ditch) Navarettia
Nolina interrata
C2
C2
C2
C2
C2
Cl
Dehesa Nolina
Opuntia parryi var. serpentina C2
Snake Cholla
Opuntia wigginsii C2
Wiggins' Cholla
Orcuttia calif omica Cl
California Orcutt Grass
Orobanche parishu ssp. brachyloba C2
Short-lobed Broomrape
Orthocarpus lasiorhynchus C2
San Bernardino Mtns. Owls-clover
Perideridia gairdneri ssp. gairdneri C2
Gairdner's Yampah
torreyana ssp. torreyana
Torrey Pine
C2
Rare
SE
None
None
SE
None
None
None
None
SE
None
None
SE
None
None
None
None
List IB, 3-3-3
List IB, 3-3-3
List 4, 1-1-2
List IB, 3-1-2
List IB, 2-3-2
List IB, 3-2-3
List IB, 2-2-2
List 3, 2-3-2
List IB, 2-3-2
List IB, 3-3-2
List IB, 3-3-2
List IB, 3-1-2
List IB, 2-3-2
List IB, 2-2-2
List IB, 1-2-3
List IB, 1-2-3
List IB, 3-2-3
Poa atropurpurea Cl
San Bernardino Blue Grass
Pogogyne abramsii FE
San Diego Mesa Mint
Pogogyne nudiuscula Cl
Otay Mesa Mint
Ribes canthariforme C2
Moreno Currant
Rorippa gambellii C2
Gambel's Water Cress
Rubus glaucifolius var. ganderi C2
Cuyamaca Raspberry
Salvia eremostachya C2
Desert Sage
Senecio ganderi C2
Gander's Butterweed
Solanum tenuilobatum C2
Narrow-leaved Nightshade
Tetracoccus dioicus C2
Parry's Tetracoccus
Xylorhua orcuttii C2
Orcutt's Woody Aster
None List IB, 2-2-3
SE List IB, 2-3-3
SE List IB, 3-3-2
None List IB, 3-1-3
None List IB, 3-3-2
None List IB, 3-1-3
None List 4, 1-1-1
Rare List IB, 3-2-3
None List IB, 3-1-3
None List IB, 3-2-2
None List IB, 2-1-2
California Native Plant Society 1988
List of Species Designations
IB: Species is rare or endangered in California and elsewhere.
3: Plants about which more information is needed.
2: Rare or endangered in California, more common elsewhere.
4: Plants of limited distribution (a watch list).
Note: Plants on CNPS list IB meet CDFG criteria for Rare of Endangered Listing.
R-E-D Code
R - (Rarity)
1 - Rare, but found in sufficient numbers and distributed widely enough that the potential
for extinction or extirpation is low at this time.
2 - Occurrence confined to several populations or one extended population.
3 - Occurrence limited to one or a few highly restricted populations, or present in such
small numbers that it is seldom reported.
E - (Endangerment)
1 - Not endangered
2 - Endangered in a portion of its range
3 - Endangered throughout its range
D - (Distribution)
1 - More or less widespread outside California
2 - Rare outside California
3 - Endemic to California
D D 0
ENVIRONMENTAL IMPACT REPORTS
AND OTHER DOCUMENTS
CONSULTED
BIOLOGICAL RESOURCES AND HABITAT ANALYSIS
in support of the CITY OF CARLSBAD HABITAT MANAGEMENT PLAN
Agua Hedionda EIR (329)
Alanda Project EIR (83-5)
Alanda Project EIR (83-5, Part II)
Anderson EIR (81-10)
Airport Business Center EIR (81-6)
Arroyo La Costa Master Plan EIR (86-2)
Batiquitos Lagoon EIR (84-3)
Batiquitos Pointe EIR (82-4)
Bressi Ranch EIR (83-10)
Buena Vista Park Plaza EIR (82-5)
Calavera EIR (403)
Camino Hills EIR (83-9)
Carlsbad Highlands EIR (80-8)
Carlsbad Highlands EIR (80-8, Supplemental EIR)
Carlsbad Land Investors EIR (83-8)
Carlsbad Oaks (81-4)
City Operations Center EIR (82-1)
Coast Waste Management EIR (84-1)
Cannon Road: Reach 1 EIR (87-1)
Del Mar Financial EIR (83-1, General Information)
Evans Point EIR (85-3)
Hosp Grove EIR (86-4)
HPI Development EIR (83-2)
Hunt Properties EIR (83-2, DEIR General Plan)
Hunt Properties EIR (83-2, Annexation of City of Carlsbad)
Huntington Palomar Project EIR (81-9)
Kelly Ranch EIR (83-4)
La Costa Northeast EIR (149)
La Costa Vale EIR (35)
Lake Calavera EIR (89-3)
Macario Canyon Park EIR (80-9)
Occidental Land Inc. EIR (81-1)
Poinsettia Lane EIR (82-6)
Pointe San Malo Condominium EIR (80-4)
Rancho Carillo EIR (80-7)
Rancho Del Cerro EIR (85-2)
Rancho La Costa EIR (114)
Ranch Santa Fe Road EIR (91-1)
Robert's Group Project EIR (83-7)
Robertson Ranch EIR (81-7)
Royal Palms EIR (85-5)
Santa Fe Glens EIR (276)
Santa Fe Knolls Preliminary Environmental Information (85-5)
Seabluff EIR (81-8)
Seawall EIR (84-2)
Sherman/Southers EIR (81-5)
Stagecoach Park EIR (84-5)
Telescope Point EIR (81-2)
Windsong Shores Focus EIR (83-3)
Wooley Annexation EIR (82-3)
EXHIBIT 2
Revised and Updated Work Program for
Completion of the Habitat Management Plan (HMP)
PHASE III
Taskl
Preserve Design and Gap Analysis
A. Based on analysis completed in Phase II, identify most valuable preserve areas.
B. Identify habitat areas currently protected
1. Constrained lands.
2. Open Space under existing General Plan or zoning.
3. Existing project-related open space.
4. Other already protected areas.
C. Identify habitat areas with potential to be protected by proposed Open Space and
Conservation Resource Management Plan.
D. Identify high priority habitat areas not already protected.
E. Identify appropriate buffers, corridors, and regional connections.
F. Identify habitat areas where development should be allowed if compensation made
for habitat loss.
G. Identify areas where development can occur without impacts to habitat.
H. Identify Final Recommended Preserve and Corridor System Boundaries.
Task 2
Coordination with Other Agencies and Programs, including:
A. U.S. Fish and Wildlife Service.
B. State of California Department of Fish and Game and Natural Communities
Conservation Program.
C. North County Wildlife Forum.
D. City of San Diego Multi-Species Conservation Plan.
Task 3
Coordination with Carlsbad Development Policy Documents
A. Coordinate with Open Space and Conservation Resource Management Plan.
B. Coordinate with update of Land Use Element of General Plan.
C. Integration of HMP into General Plan.
Task 4
Establish Legal Framework for Implementation of HMP
A. Determine legal parameters and mechanisms for acquisition of land, such as
"friendly condemnation", open space easement, etc.
B. Draft ordinances to provide for transfer of development rights, establishment of new
zoning categories, and other land use tools.
C. Evaluate institutional options for preserve ownership and management.
Tasks
Mechanisms for Acquisition/Protection of High Priority Habitat Areas Not Already
Protected
A. Acquisition and Funding Strategy
1. Identify appropriate funding mechanisms, including local, state, and federal
sources.
2. Evaluate feasibility of candidate funding mechanisms.
B. Funding for Maintenance and Management
1. Estimate management and maintenance costs.
2. Evaluate sources of funding for management and maintenance, including
endowment and maintenance assessment district.
C. Other Mechanisms for Acquisition/Protection
1. Transfer of Development Rights.
2. Use of General Plan/zoning for protection.
Task6
Management and Maintenance
A. Evaluate need for revegetation/restoration in Preserve and Corridor System.
B. Identify allowable and prohibited uses within Preserve and Corridor System.
C. Identify points of public access into System, and explore methods for controlling
access.
D. Identify and evaluate alternatives for enforcement.
E. Identify compatible and incompatible uses adjacent to System, and explore methods
for minimizing indirect impacts of adjacent uses.
F. Develop public education program.
G. Identify need for interpretive signing and potential for interpretive center.
H. Develop process for determining final institutional arrangements.
Task 7
City Council Status Report and Recommendation to Proceed.
PHASE IV
Task 8
Prepare final Preserve and Corridor System Implementation and Management Report
Task 9
Pursue Citywide Habitat Conservation Plan (HCP)
A. Prepare Draft HCP document.
B. Environmental Documentation
1. Conduct environmental scoping to determine extent of environmental review.
2. Issue Notice of Preparation and proceed with preparation of appropriate
documents in compliance with California Environmental Qualtiy Act (CEQA) and
National Environmental Policy Act.
C. Consider addressing necessary General Plan amendments and related actions in
CEQA review.
D. Finalize HCP document and environmental documents for adoption by City, U. S.
Fish and Wildlife Service, and California Department of Fish and Game.
Task 10
Presentation of final documents to City Council for adoption.
ALL RECEIVED
Hofman Planning
Associates
September 1, 1992
City Councilmembers
City of Carlsbad
1200 Carlsbad Village Drive
Carlsbad, CA 92008
SUBJECT: Carlsbad HMP - Biological Resources and Habitat Analysis
Dear Councilmembers:
Thank you for the opportunity to provide input on the Biological Resources and Habitat Analysis
for the Carlsbad Habitat Management Program (HMP). We recognize that this report marks a
significant milestone in the HMP work program and represents the diligent efforts of all parties
involved in the HMP. The purpose of this letter is to support the staffs recommendations
regarding the HMP and to move forward with Phase III of the work program as soon as
possible. However, we have a few concerns which we wish to document at this time but which
we are confident can be addressed during Phase III.
HPA has reviewed the Biological Resources and Habitat Analysis and has spoken with staff
regarding the intent of the Preserve Planning Areas. It is our understanding that the Preserve
Planning Areas (PPAs) represent land within Carlsbad from which a preserve could ultimately
be constructed. Only a portion of the entire PPA area would be set aside if a preserve is
implemented, not the entire PPA. In addition, it is our understanding that while some land may
already be publicly held, any privately held land would either be: (1) included because there are
already mechanisms which will allow for it to be set aside (such as the 15 % growth management
Open Space requirement); or (2) acquired through some mutually agreeable form of
compensation. We feel it is important to recognize that the amount of land ultimately preserved
will be dependent on the availability of financing to acquire the property for the preserve. We
look forward to working with staff to assess the financial feasibility of the preserve during Phase
III of the work program.
We would also like to express concern regarding the buffer widths proposed in Section 5.3.
While the Biological Resources and Habitat Analysis does state that the recommended widths
should be only guidelines, we feel it is important to allow for consideration of biological
sensitivity of habitat and to maintain maximum flexibility in determining buffer widths during
environmental review of affected projects.
On behalf of several property owners, HPA has worked with staff to refine information in the
document to reflect the most accurate information available, however, there remain a few areas
HMP Comments, P. 2
September 1. 1992
of property owner concern. The Carrillo Ranch property owners feel that the location of
Wildlife Corridor WC2-5B would better serve the needs of wildlife if it were shifted to the west
of Melrose Drive north of Palomar Airport Road to take advantage of existing steep slopes
covered with native vegetation. Once it crosses Palomar Airport Road, it should be realigned
to take advantage of a large steep north-south trending canyon on the easterly edge of the Bressi
Ranch property. In its present location the corridor crosses future Melrose Avenue and would
severely impact the developability of the site with questionable wildlife benefits. Also, the
Sunny Creek area property owners in Zone 15 have concerns regarding the inclusion of land in
the Preserve Planning Areas which has been farmed for several generations and does not
currently support native vegetation. Staff is aware of these concerns and has agreed to work
with the property owners during the completion of Phase III to resolve these and any other
concerns which may arise. These concerns will be documented to the HMP Advisory Group.
This is acceptable to the property owners, who do not wish to delay the progress of the program.
In summary, we believe this program represents a unique opportunity, if it is implemented with
flexibility, to provide for wildlife preservation while allowing for the continued economic
development of the City. Carlsbad's proactive approach to this difficult situation is setting an
example for other jurisdictions to follow.
Thank you for the opportunity to participate in the Habitat Management Program. Lisa King
of our staff will be in attendance at the City Council meeting to answer any questions you may
have.
Sincerely,
Bill Hofman
BH:LK
cc: Ray Patchett
Marty Orenyak
Michael Holzmiller
Don Rideout
City Clerk