HomeMy WebLinkAbout3338; Agua Hedionda & Calavera Creek Dredging; College & Cannon Carlsbad High School Site Wildlife Study; 2010-04-01College and Cannon Carlsbad High School Site
Wildlife Movement Study
Prepared fbr:
Carlsbad Unified School District
6225 El Camino Real
Carlsbad. California 92009
Prepared by:
DUDEK
605 Third Street
Encinitas, California 92024
Contuck Mike Howard
College and Cannon Carlsbad High School Sie
Wildlife Movement Study
TABLE OF CONTENTS
Section Paae No .
........................ ......*. .... .......... 1.0 INTRODumOM ..-..-...- ............... - ...-. .... - - "1
1.1 Wildlife Habitat Connectivity Primer .................................................................... 1
.*** .. ...... .... .............. ..... ............... 2.0 PROJFKTSETTING ... ........- .-. ........ -. 14
3.0 METHODS AND SURVEY CONDITIONS .................................... - ..-..-.. 14
3.1 Literature Review .................................................................................................. 14
3.2 field Reconnaissance ........................................................................................ 16
....................................................................................... 3.2.1 Rod-kiIlSurvey 16
......................................................................................... 3.2.2 Track Survey 19
............................................................................................ 3.2.3 Camerastudy 19 ... ............................................................................................... 3.3 Survey L~rn~kihons 20
4.0 RESULTS OF SURVEYSH ......... .. ......... - ...- ......... - .......... - ..... - ................ B
4.1 Road-Kill Survey ...................................~.............................................................. 29
....................................................................................................... 4.2 TmkSurreys 30
....................................... 4.2.1 Scent Station Surveys ............................ ...... 30
............................................................................................. 4.2.2 Trailsurveys 31
....................................................................... .................... 4.3 Camera Study .........., 33
4.4 Special-status Biological Resources .................................................................... 33
........................................... ........................... 4.4.1 Special-status Wildlife ... 33
4.4.2 Wildlife Corridors and Habitat Linkages .................................................. 34
.......... ............................................................ .... . 5.0 DISCUSSION - - , - ...-..-.. 41
*.*....... .**............... ........ 6.0 L1TERATURE:CITED - ..- .... - .......................-..-...-.a
APPENDIX
List of Wildlife Observed Within Study Area
College and Cannon Carlsbad High School Site
Wildlife Movement study
INTRODUCTION
The Carlsbad Unified School District is planning to construct a new high school at the corner of
College Boulevard and Cannon Road in Carlsbad, California (Figurn 1, 2, and 3). The proposed
location for the new high school is Ajacent to the Calavera Conservation Area, a recreational
open space and core habitat area hated within the City of Cxlsbad. This is adjacent to Calavera
Hills & Robertson Ranch Habitat Conservation Area (Conservation Area) managed by the
Center for Natural Lands Management (CNLM; Figure 3). Additionally, there is an extension of
Cannon Road planned in the same vicinity. Carlsbad Unified School District is interested in
wildlife movement in the area. The proposed project is located within and adjacent to a large
block of undeveloped lands and is surrounded by a network of open Iands that occur between
neighborhds and developments in the vicinity. These areas potentially support wildlife
movement to other connected lands to the west (Agua Hedionda, Buena Vista, and Batiquitos
Lawns), north (Oceanside habitat blocks), and southeast (Elfin Forest and Lake Hdges), ztnd
other lands to the east. Dudek was contracted to perfurm a variety of wildlife movement methods
during a h-week period in Januaryffebruaq 2010, to identify wildlife movement and related
issues. This report describes the results of the wildlife movement study conductd for the
proposed project area, surrounding open space and roadways. The purpose of the wildlife
mwement study was to determine what wildlife spcies are utilizing tfie area, where movement
is occurring and the potential impact to wildlife from existing and proposed land uses.
Wildlife Habitat Connectivity Primer
A fundamental concept and central tenet of conservation biology theory is that a lack of habitat
connectivity and contiguity (usualIy referred to as habitat fragmentation and isolation) may cause
extinction of Id populations as a result of two processes: (1) reduction in total habitat area,
which reduces effective popuIation sizes; and (2) insularization of local populations, which
affects dispersal and immigration rates (Wilcox and Murphy 1 985; Wilcove et al. 1986). Wilcox
and Murphy (1985) further point wt that immigration may be impeded by conversion of natural
vegetation communities that provide habitat between occupied or potential habitat patch=, thus
inmasing the probability of extinction. This latter point is the crux of the habitat linkage
problem. That is, isolation of habitat patches accompanied by intervening inhospitable land cover
(e-g., urban development, roadways) is thought to incme the probability of permanent
extinction of local populations. Because of complex community-level interactions (e.g.,
mutualistic species, habitat guilds, keystone species), the loss of one or a few species h a
habitat patch as a direct result of habitat fragmentation (primary extinctions) may also mult in
multiple "smndary " ex tinctions within the habitat patch (Wilcox and Murphy 1 985).
College and Cannon Carlsbad High School Site
Wildlife Movement Studv
Habitat fragmentation has been linked with reduced diversity in bird species, even on adjacent
nonfragrnented habitats (Rottenborn 1999). Several studies in coastal San Diego County have
demonstrated species losses related to habitat fragmentation and isolation. Soul6 et aI. (I 988)
found very high rates of extinction in a study of the distribution of "chaparral-dependent" native
birds (the analysis included coastal sage scrub species) in isolated canyon habitac fragments.
Soul6 et al, (1988) attributed this loss to the focal species' generally low vagility and inability to
traverse urban environments. Similarly, Soul6 et al. (1992) found that fragmentation caused rapid
extinctions with predictable sequences of species loss in a suite of species including plants, birds,
and rodents in coastal sage scrub habitat. Bolger et al. (1 997) found fewer rodent species in
fragments isolated for longer periods of time and at greater isolation distances in coastal San
Diego County. Lower arthropod diversity was also observed by Bolger et al. (2000) in older and
smaller habitat fragments in the same region.
Wildlife connections also likely play a critical role in sustaining "metapopulations," which are
characterized as local populations of the same species that are partially isolated but cowed by
pathways for dispersal (irnrnigration/emigration) (Levins 1969). Local populations within a
metapopulation are subject to stochastic events, and they fluctuate depending on the rate of
dispersal between the local populations and the local rate of extinction. Patches subject to local
extirpations may be recolonized by dispersal from other source patches, provided that habitat
connectivity remains for the species. Truly or functionally isolated local populations risk
permanent extinction by a variety of causes, including simple population dynamics, loss of
genetic integrity, or stochastic environmental impacts.
DUDEK