The Santa Ana?Palomar Mountain Linkage (SAPML) represents a wildlife corridor which connects the Palomar mountain range and the Santa Ana mountain range located in southern California. The linkage provides connectivity for a variety of species including mountain lions (Felis concolor). Interstate 15 (I-15), running north and south through the linkage, along with urban and agricultural development have created a significant chokepoint for wildlife movement in the middle of the corridor. Wildlife crossing structures provide a viable means for wildlife to effectively cross a road barrier. Research contends that wildlife crossing structures should be placed along an animal?s natural route of travel. Therefore, the purpose of this research is to determine suitable wildlife crossing locations across I-15 based upon predicted movement routes for mountain lions within the SAPML Choke-Point. Knowledge of wildlife crossing locations will help to enhance the connectivity of the SAPML.
The following three research objectives are examined: (i) the validity of a least-cost path (LCP) analysis to determine potential movement routes and interstate crossing locations for mountain lions, (ii) the identification of suitable wildlife crossing locations along I-15 within the SAPML Choke-Point, and (iii) the influence of future development on the effectiveness of wildlife crossing locations within the choke-point.
The results indicate that an LCP analysis can significantly predict movement routes and interstate crossing locations for mountain lions. Wildlife crossing locations were determined along I-15 within the SAPML Choke-Point. These crossing locations coincide with drainage infrastructure which exist underneath the interstate and may be able to be reconstructed to provide feasible crossing structures for wildlife. Lastly, future development within the choke-point will disturb wildlife movement and diminish the effectiveness of wildlife crossing locations along I-15. Areas critical for connectivity have been identified for conservation.
Appendix E for: Final report re NCCP-Local Assistance Grant # P1750301 from
California Dept. of Fish and Wildlife and SANDAG – UCD agreement
#A37682/MOU #5005298 Awarded to the University of California, Davis
Wildlife Health Center.
Although the fragmentation of the natural landscape of coastal southern California, USA,
is accelerating, large-scale assessments of regional connectivity are lacking. Because of their large area
requirements and long dispersal movements, mammalian carnivores can be effective focal species to
use when evaluating landscape-level connectivity. Our goal was to make an initial assessment of the
extent of landscape-level connectivity in coastal southern California using mountain lions (Fe/is
concolor [Linnaeus]) and bobcats (Felis rufus [Shreber]) as focal species. We first characterized habitat
preferences for mountain lions and bobcats from previously derived habitat relationship models for
these species; the resulting maps provided a coarse view of habitat preferences for use at regional scales.
We then constructed GIS models to evaluate the disturbance impact of roadways and development,
major determinants of carnivore distribution and abundance in the south coast region. Finally, we
combined the habitat relationship models with the disturbance impact models to characterize habitat
connectivity for mountain lions and bobcats in the ecoregion. Habitat connectivity in the ecoregion
appeared higher for bobcats than for mountain lions due in part to higher habitat suitability for bobcats
in coastal lowland areas. Our models suggest that much of the key carnivore habitat in the coastal
southern California is at risk; over 80% of high suitability habitat and over 90% of medium suitability
habitat for carnivores is found in the least protected land management classes. Overall, these models
allow for (I) identification of core habitat blocks for carnivores and key landscape connections between
core areas, (2) evaluation of the level of protection of these areas, and (3) a regional framework within
which to develop and coordinate local management and conservation plans.
Pumas (Puma concolor; also known as mountain lions and cougars) in southern California live among a burgeoning human
population of roughly 20 million people. Yet little is known of the consequences of attendant habitat loss and
fragmentation, and human-caused puma mortality to puma population viability and genetic diversity. We examined genetic
status of pumas in coastal mountains within the Peninsular Ranges south of Los Angeles, in San Diego, Riverside, and
Orange counties. The Santa Ana Mountains are bounded by urbanization to the west, north, and east, and are separated
from the eastern Peninsular Ranges to the southeast by a ten lane interstate highway (I-15). We analyzed DNA samples from
97 pumas sampled between 2001 and 2012. Genotypic data for forty-six microsatellite loci revealed that pumas sampled in
the Santa Ana Mountains (n = 42) displayed lower genetic diversity than pumas from nearly every other region in California
tested (n = 257), including those living in the Peninsular Ranges immediately to the east across I-15 (n = 55). Santa Ana
Mountains pumas had high average pairwise relatedness, high individual internal relatedness, a low estimated effective
population size, and strong evidence of a bottleneck and isolation from other populations in California. These and
ecological findings provide clear evidence that Santa Ana Mountains pumas have been experiencing genetic impacts
related to barriers to gene flow, and are a warning signal to wildlife managers and land use planners that mitigation efforts
will be needed to stem further genetic and demographic decay in the Santa Ana Mountains puma population
Jointly considering the ecology (e.g., habitat use) and genetics (e.g., population genetic structure and diversity) of a species can increase understanding of current
conservation status and inform future management practices. Previous analyses indicate that mountain lion (Puma concolor) populations in California are genetically
structured and exhibit extreme variation in population genetic diversity. Although
human development may have fragmented gene flow, we hypothesized the quantity and quality of remaining habitat available would affect the genetic viability of
each population. Our results indicate that area of suitable habitat, determined via
a resource selection function derived using 843,500 location fixes from 263 radio collared mountain lions, is strongly and positively associated with population genetic
diversity and viability metrics, particularly with effective population size. Our results
suggested that contiguous habitat of ?10,000 km2
may be sufficient to alleviate the
negative effects of genetic drift and inbreeding, allowing mountain lion populations
to maintain suitable effective population sizes. Areas occupied by five of the nine
geographic–genetic mountain lion populations in California fell below this habitat
threshold, and two (Santa Monica Area and Santa Ana) of those five populations lack
connectivity to nearby populations. Enhancing ecological conditions by protection
of greater areas of suitable habitat and facilitating positive evolutionary processes
by increasing connectivity (e.g., road-crossing structures) might promote persistence
of small or isolated populations. The conservation status of suitable habitat also appeared to influence genetic diversity of populations. Thus, our results demonstrate
that both the area and status (i.e., protected or unprotected) of suitable habitat influence the genetic viability of mountain lion populations
Habitat remnants in urbanized areas typically conserve biodiversity and serve the recreation and urban open-space needs of human populations. Nevertheless, these goals can be in conflict if human activity negatively affects wildlife. Hence, when considering habitat remnants as conservation refuges it is crucial to understand how human activities and land uses affect wildlife use of those and adjacent areas.We used tracking data (animal tracks and den or bed sites) on 10 animal species and information on human activity and environmental factors associated with anthropogenic disturbance in 12 habitat fragments across San Diego County, California, to examine the relationships among habitat fragment characteristics, human activity, and wildlife presence. There were no significant correlations of species presence and abundance with percent plant cover for all species or with different land-use intensities for all species, except the opossum (Didelphis virginiana), which preferred areas with intensive development. Woodrats (Neotoma spp.) and cougars (Puma concolor)
were associated significantly and positively and significantly and negatively, respectively, with the presence of horses. Raccoons (Procyon lotor) and coyotes (Canis latrans) were associated significantly and negatively and significantly and positively, respectively, with plant bulk and permanence. Cougars and gray foxes (Urocyon cinereoargenteus) were negatively associated with the presence of roads. Roadrunners (Geococcyx californianus) were positively associated with litter. The only species that had no significant correlations with any of the environmental variables were black-tailed jackrabbits (Lepus californicus) and mule deer (Odocoileus hemionus). Bobcat tracks were observed more often than gray foxes in the study area and bobcats correlated significantly only with water availability, contrasting with results from other studies. Our results appear to indicate that maintenance of habitat fragments in urban areas is of conservation benefit to some animal species, despite human activity and disturbance, as long as the fragments are large.
Wide-ranging large carnivores pose myriad challenges for conservation, especially in highly fragmented landscapes. Over a 13-year period, we combined monitoring of radio collared pumas (Puma concolor) with complementary multi-generational genetic analyses
Migration is essential for maintaining genetic diversity among populations, and pumas (Puma concolor) provide an excellent model for studying the genetic impacts of migrants on populations isolated by increasing human development. In densely populated southern California, USA, puma populations on the east and west side of interstate highway 15 (I-15) have become fragmented into a small inbred population on the west side (Santa Ana Mountains) and a relatively larger, more diverse population on the east side (Eastern Peninsular Range). From 146 sampled pumas, genetic analyses indicate seven pumas crossed I-15 over the last 15 years, including four males from west to east, and three males from east to west. However, only a single migrant (named M86) was detected to have produced offspring and contribute to gene flow across the I-15 barrier. Prior to the M86 migration, the Santa Ana population exhibited inbreeding and had significantly lower genetic diversity than the Eastern Peninsular Range population. After M86 emigrated, he sired 11 offspring with Santa Ana females, decreasing inbreeding measures and raising heterozygosity to levels similar to pumas in the Eastern Peninsular Range. The emigration of M86 also introduced new alleles into the Santa Ana population, although allelic richness still remained significantly lower than the Eastern Peninsular population. Our results clearly show the benefit of a single migrant to the genetics of a small, isolated population. However, ongoing development and habitat loss on both sides of I-15 will increasingly strengthen the barrier to successful migration. Further monitoring, and potential human intervention, including minimizing development effects on connectivity, adding or improving freeway crossing structures, or animal translocation, may be needed to ensure adequate gene flow and long-term persistence of the Santa Ana puma population.
The importance of examining multiple hierarchical levels when modeling resource use for
wildlife has been acknowledged for decades. Multi-level resource selection functions have
recently been promoted as a method to synthesize resource use across nested organizational
levels into a single predictive surface. Analyzing multiple scales of selection within
each hierarchical level further strengthens multi-level resource selection functions. We
extend this multi-level, multi-scale framework to modeling resistance for wildlife by combining
multi-scale resistance surfaces from two data types, genetic and movement. Resistance
estimation has typically been conducted with one of these data types, or compared between
the two. However, we contend it is not an either/or issue and that resistance may be bettermodeled
using a combination of resistance surfaces that represent processes at different
hierarchical levels. Resistance surfaces estimated from genetic data characterize temporally
broad-scale dispersal and successful breeding over generations, whereas resistance
surfaces estimated from movement data represent fine-scale travel and contextualized
movement decisions. We used telemetry and genetic data from a long-term study on pumas
(Puma concolor) in a highly developed landscape in southern California to develop a multilevel,
multi-scale resource selection function and a multi-level, multi-scale resistance surface.
We used these multi-level, multi-scale surfaces to identify resource use patches and
resistant kernel corridors. Across levels, we found puma avoided urban, agricultural areas,
and roads and preferred riparian areas and more rugged terrain. For other landscape features,
selection differed among levels, as did the scales of selection for each feature. With
these results, we developed a conservation plan for one of the most isolated puma populations
in the U.S. Our approach captured a wide spectrum of ecological relationships for a
population, resulted in effective conservation planning, and can be readily applied to other
wildlife species.
This 2013 Wildland Fire Workshop focused on Southern California and landscape level fires occurring in the last decade. This workshop brought together land managers, researchers, and fire management personnel to continue the discussions on the topic of wildland fire impacts to at risk natural resources. The purpose of the workshop was to present, collaborate, and plan wildland fire-related research, management, responses, and future recovery as it applies to the at-risk natural resources of San Diego County.
Recording of the may 28, 2025 SDMMP Management and Monitoring Coordination Meeting. Topics: "An update on the UC Davis Mountain Lion Research Project" (Fernando Najera, UC Davis)
Recording for the January 27, 2021 Management and Monitoring Coordination Meeting. Dr. Winston Vickers shares an "Update on the UC Davis Southern California Mountain Lion Project, as well as Results of Recent Research Elsewhere in the State".
Mountain lions (Puma concolor, puma, cougars) are top carnivores and important ecological regulators that roam widely throughout the San Diego County landscape. Puma concolor is a named species in regional conservation plans. Because of the extensive areas required by each mountain lion, multiple Natural Conservation Community Planning (NCCP) areas are often utilized by a single individual. Thus, connectivity within and between NCCPs is important for long-term health and persistence of mountain lions in the landscape, and proper NCCP function. In addition to the currently approved NCCP areas in Southern California, San Diego County is in advanced stages of preparing a conservation preserve design for its North County Multiple Species Conservation Program (NCMSCP). This research project uniquely combined camera, GPS-collar, and mortality data with state of the art genetic analyses and modeling, and an expert workshop, to produce the most comprehensive assessment to date of mountain lion habitat use and connectivity within, and adjacent to, the NCMSCP area.
This study uniquely combined camera, GPS location, and mortality data from mountain lions in the region, with state of the art genetic analyses, advanced habitat and movement modeling, and expert opinion to provide as complete an assessment as has been done to date of the factors that affect mountain lion persistence in the NCMSCP and surrounding NCCP areas. The research team’s focus was to provide key information about mountain lion movement and wildlife connectivity that is currently lacking at puma-specific scales in the NCMSCP and adjacent NCCP areas in order to assist in prioritization of habitat for conservation of this species and others. The team also focused on informing highway planners about best locations for wildlife crossing improvements for highways in the area.
Mountain lions (Puma concolor, puma, cougars) are top carnivores and important ecological regulators that
roam widely throughout the San Diego County landscape. Puma concolor is a named species in regional
conservation plans. Because of the extensive areas required by each mountain lion, multiple Natural
Conservation Community Planning (NCCP) areas are often utilized by a single individual. Thus, connectivity
within and between NCCPs is important for long-term health and persistence of mountain lions in the
landscape, and proper NCCP function. In addition to the currently approved NCCP areas in Southern California,
San Diego County is in advanced stages of preparing a conservation preserve design for its North County
Multiple Species Conservation Program (NCMSCP). This research project uniquely combined camera, GPScollar,
and mortality data with state of the art genetic analyses and modeling, and an expert workshop, to
produce the most comprehensive assessment to date of mountain lion habitat use and connectivity within, and
adjacent to, the NCMSCP area.
This assessment of mountain lion use of core conserved lands and linkages in western San Diego County (Figures 2 – 4, Tables 1 and 2) was undertaken by the UC Davis Wildlife Health Center as a part of its ongoing Southern California Mountain Lion project. GPS-collaring of mountain lions was undertaken in order to acquire location and movement data from individual lions utilizing core conserved areas and linkages that have been designated by the county. Certain cores and linkages were not judged by experts advising the county to be likely to accommodate regular use by mountain lions (primarily those cores west of I-15), thus those areas were not a focus of this study. However, some trail camera monitoring was done west of I-15 to evaluate the validity of this expectation.
As prescribed in the above listed contract with the San Diego County Association of Governments
(SANDAG), personnel from the UC Davis Wildlife Health Center (UCD-WHC) and Western Tracking
Institute (WTI) (collectively UC Davis Team) have initiated field activities relating to the study of
connectivity of conserved lands in portions of San Diego County for mountain lions. The aforementioned
contract was finalized in May, 2012 and field activities began almost immediately. Some pre-contract field
scouting and trail camera placement and monitoring was conducted in the fall of 2011 and early 2012.
The results from trail cameras placed originally during that time and subsequently incorporated in this
field effort are also reported here.
As prescribed in the above listed contract with the San Diego County Association of Governments (SANDAG),
personnel from the UC Davis Wildlife Health Center (UCD-WHC) and Western Tracking Institute (WTI)
(collectively UC Davis Team) have been conducting field activities relating to the study of connectivity of
conserved lands in portions of San Diego County for mountain lions. The aforementioned contract was finalized
in May, 2012 and field activities began almost immediately. Some pre-contract field scouting and trail camera
placement and monitoring was conducted in the fall of 2011 and early 2012. The results from trail cameras
placed originally during that time and subsequently incorporated in this field effort are also reported here.
Data reported is as of November 1, 2013 except where noted. This report is the third 6-month report required by
this contract.
This document seeks to provide the San Diego Association of Governments (SANDAG) a
summary of the activities on Task 2 (Agreement #A37682/MOU #5005298/ AMENDMENT NO.
2 (S890571)) related to the educational efforts, and testing and use of deterrent devices and
strategies, undertaken by the UC Davis Wildlife Health Center mountain lion project team with
the goal of reducing domestic animal and mountain lion mortalities in the County. Being killed
after depredating domestic animals, usually small livestock or pets, is the number one source
of mortality for mountain lions in San Diego County and California as a whole (Benson et al.
2023, Vickers et al. 2015). Low overall survival rates are a concern in the San Diego County
mountain lion population, and reducing livestock predation and associated mountain lion
mortalities is a high priority. Our UC Davis mountain lion study team has worked to reduce
losses of domestic animals and mountain lions for many years. This report details the work
conducted under this contract, as well as other funding, to advance animal owner education
regarding proper husbandry of their domestic animals, and to explore strategies and tools that
can assist owners in that effort. This is one of the goals of our study team not only in San
Diego County but throughout California.
This document seeks to provide the San Diego Association of Governments (SANDAG) with the UC
Davis Wildlife Health Center recommendations on scientific techniques for long-term monitoring of
mountain lions in southern California that can be applied under the scope of work of the San Diego
Management and Monitoring Program (https://sdmmp.com/metrics/).
This mountain lion (Puma concolor; puma, cougar) study is headed by Dr. Winston Vickers of the
Wildlife Health Center at UC Davis (WHC). David Garcelon of the Institute for Wildlife Studies (IWS)
is the PI for the northeastern California part of the study, and Dr. Jessica Sanchez of the San Diego Zoo
Wildlife Alliance was a key contributor to several study elements in Southern California. From midApril till December 1, 2022, Dr. Justin Dellinger co-Directed activities in all of the study areas with Dr.
Vickers. Dr. Fernando Najera is expected to join the study as co-Director in March 2023. Dr. Vickers
prepared this report with contributions from the other project collaborators.
Overall activities and research into mountain lions by the UC Davis WHC have been ongoing since the
first capture of a mountain lion in the study in March of 2001. Over the course of this long term study,
cougars were captured, sampled, and GPS collared in Orange, Riverside, San Diego, Modoc, Lassen
Counties, and Kern Counties, and future capture activities are expected in the Gabilan Range and
Pacheco Pass either in or in close proximity to Santa Clara, San Benito, Santa Cruz, and Monterey
Counties (Figure 2).
The title of this Project is “Santa Ana Mountains to eastern Peninsular Range Conservation
Connectivity Infrastructure Planning Project for Interstate 15 and Closely Associated Roadways”
(funded through this Agreement by the Natural Community Conservation Planning (NCCP) Local
Assistance Grant (LAG) Program) and is conducted coincident with the Project titled “Mountain
Lion Linkage Assessment along SR’s 76,78, and 79, and testing of Hazing Devices in Western San
Diego County (funded by the San Diego County Association of Governments), and The Nature
Conservancy (Conservancy). In-kind support is being provided by San Diego State University’s
Santa Margarita River Ecological Reserve (SMER), the Western Riverside County Regional
Conservation Authority (RCA), and California Department of Transportation (Caltrans). The lead
entity on the project is the Karen C. Drayer Wildlife Health Center at the University of California,
Davis (UCD-WHC), with collaborators from the California Polytechnic University, Pomona (CPP)
and the Conservancy. Mountain lion research has been conducted by researchers from the
UCD-WHC in southern California since 2001.
This quarterly report to SANDAG (first quarter 2023) relates to the project titled “Mountain
Lion Linkage Assessment along SR’s 76,78, and 79, and testing of Hazing Devices in Western San
Diego County” (funded by the San Diego County Association of Governments), and The Nature
Conservancy (TNC), with amendments / expansion in September 2021 to include testing of
methods of mountain lion population monitoring and estimation, and development of plans for
long term monitoring of mountain lion populations in San Diego County (hereafter “SANDAG-funded project”) .
This cougar (Puma concolor; puma, mountain lion) study is headed by Dr. Winston Vickers of the
Wildlife Health Center at UC Davis. Dave Garcelon leads the northeastern California part of the study.
Dr. Vickers prepared this report.
Since 2001, this study has been conducted in Orange, Riverside, and San Diego Counties in southern
California south of Los Angeles, and incorporates mountainous areas including the Santa Ana
Mountains portion of the Peninsular Ranges (west of I-15) and the eastern Peninsular Mountain Ranges
east of I-15 (Figure 1). In late 2015, an amendment to our SCP was submitted to allow expansion of the
study scope and region to study of cougar ecology and interactions with pronghorn antelope in the
northeastern corner of California (Modoc, Lassen, and Siskiyou Counties) (Figure 2). This second part
of our study is being conducted in collaboration with, and with the support of, Dave Garcelon and the
Institute for Wildlife Studies (IWS). The SCP amendment was approved in January 2016 and trail
camera monitoring and puma capture and GPS collaring activities, along with feeding site
investigations, have been conducted since that time.
The title of this Project is “Santa Ana Mountains to eastern Peninsular Range Conservation Connectivity Infrastructure Planning Project for Interstate 15 and Closely Associated Roadways” (funded through this Agreement by the Natural Community Conservation Planning (NCCP) Local Assistance Grant (LAG) Program) and is conducted coincident with the Project titled “Mountain Lion Linkage Assessment along SR’s 76,78, and 79, and testing of Hazing Devices in Western San Diego County (funded by the San Diego County Association of Governments), and The Nature Conservancy (Conservancy). In-kind support is being provided by San Diego State University’s Santa Margarita River Ecological Reserve (SMER), the Western Riverside County Regional Conservation Authority (RCA), and California Department of Transportation (Caltrans). The lead entity on the project is the Karen C. Drayer Wildlife Health Center at the University of California, Davis (UCD-WHC), with collaborators from the California Polytechnic University, Pomona (CPP) and the Conservancy. Mountain lion research has been conducted by researchers from the UCD-WHC in southern California since 2001.
Monitoring species use of habitat linkages and wildlife corridors is one component of the MSCP Biological Monitoring Plan (Ogden 1996). The monitoring plan was developed to document compliance with the MSCP, measure the effectiveness of the conservation program, and inform adaptive management decisions. This study was designed to address the following questions: Are the wildlife corridors identified in the subarea plans functional? What large mammals (deer, mountain lion, bobcat, coyote) and mesopredators use the linkages? What potential constraints to animal movement exist in these areas? Where are habitat restoration or other management actions needed to facilitate animal movement? Does the Scripps-Poway Parkway underpass function effectively for wildlife movement? What survey methods are most efficient in identifying corridor use and evaluating corridor function for each target species?
A 7-mile stretch along the I-15 in the Temecula, CA region is being looked at in
regards to its impact on mountain lion preservation. This area of urbanization serves as a
main cutoff between two populations of mountain lions: one on the east side of the
freeway, and one approximately 10 miles northwest of that population. Figure 1.1 shows
the GPS collar tracking data of the two aforementioned mountain lions that are
separated by the I-15. The yellow dots represent the movement of the mountain lions
within their respective regions.
Winston Vickers from University of California, Davis, has been leading a team in
the gathering of data regarding the Santa Ana Mountain Lion population. For the past 15
years, the population of mountain lions in the Santa Ana mountain regions and the
Eastern Peninsula Mountains has been dwindling due to a variety of reasons. The
Nature Conservancy, and other supporting Ecologists, believe that depredation permits,
vehicle strikes, fires, and urbanization are some of the key factors that contribute to the
unsuccessful reproduction rates found within these populations. After looking at the
studies, along with evidence from the professionals, it was determined that the
urbanization of the surrounding area was the most impactful towards the separation of
the lions, as well as the greatest potential for improvement.
We investigated the role of large-scale wildfires on the relative abundance of carnivores at two study areas within San Diego County of southern California, 1) Santa Ysabel Open Space Preserve and 2) Rancho Jamul Ecological Reserve-Hollenbeck Canyon Wildlife Area. In October and November of 2003, large-scale fires burned approximately 130,000 ha of San Diego County. To assess fire impacts on local carnivore communities, we collected data using two sampling techniques, 1) track surveys with baited scent stations and 2) remotely triggered camera stations. Sampling prior to the fires was conducted between May 2001 and June 2003, while post-burn sampling was conducted between August 2006 and September 2007. We calculated the relative abundance of carnivore species for each track transect and camera station, comparing pre-burn and post-burn abundance indices.
Fifteen medium to large mammal species were detected across Santa Ysabel and Rancho Jamul at track transects and camera stations. We detected 11 native species including mountain lion (Puma concolor), mule deer (Odocoileus hemionus), coyote (Canis latrans), bobcat (Felis rufus), badger (Taxidea taxus), gray fox (Urocyon cinereoargenteus), raccoon (Procyon lotor), striped skunk (Mephitis mephitis), spotted skunk (Spilogale gracilis), opossum (Didelphis virginiana), and
long-tailed weasel (Mustela frenata). We also detected four species typically associated with humans including, domestic cow (Bos taurus), domestic horse (Equus caballus), domestic dog (Canis familiaris), and domestic cat (Felis catus). Ten of the native species (badger excluded) and two human-associated species (domestic horse and domestic dog) were documented within both study sites. Within Santa Ysabel and Rancho Jamul, we found little evidence that the 2003 wildfires affected the relative abundance of the carnivore species for which we gathered sufficient data. Most of the species we studied seemed capable of persisting in the patchwork of unburned and burned
habitats resulting from these wildfires. In addition, the effects of the fires were likely short term for most carnivore species. We did not begin post-burn monitoring until nearly three years after the wildfires of 2003, by which time we likely missed the more dramatic immediate responses to wildfire. Overall, we suspect the indirect effects of wildfires, such as changes in habitat suitability and predator-prey dynamics, were largely responsible for the minor changes we observed
The title of this Project is “Santa Ana Mountains to eastern Peninsular Range Conservation
Connectivity Infrastructure Planning Project for Interstate 15 and Closely Associated Roadways”
(funded through this Agreement by the Natural Community Conservation Planning (NCCP) Local
Assistance Grant (LAG) Program) and is conducted coincident with the Project titled “Mountain
Lion Linkage Assessment along SR’s 76,78, and 79, and testing of Hazing Devices in Western San
Diego County (funded by the San Diego County Association of Governments), and The Nature
Conservancy (Conservancy). In-kind support is being provided by San Diego State University’s
Santa Margarita River Ecological Reserve (SMER), the Western Riverside County Regional
Conservation Authority (RCA), and California Department of Transportation (Caltrans). The lead
entity on the project is the Karen C. Drayer Wildlife Health Center at the University of California,
Davis (UCD-WHC), with collaborators from the California Polytechnic University, Pomona (CPP)
and the Conservancy. Mountain lion research has been conducted by researchers from the
UCD-WHC in southern California since 2001.
We investigated the role of large-scale wildfires on the relative abundance of carnivores at
two study areas within San Diego County of southern California, 1) Santa Ysabel Open Space
Preserve and 2) Rancho Jamul Ecological Reserve-Hollenbeck Canyon Wildlife Area. In October
and November of 2003, large-scale fires burned approximately 130,000 ha of San Diego County. To
assess fire impacts on local carnivore communities, we collected data using two sampling
techniques, 1) track surveys with baited scent stations and 2) remotely triggered camera stations.
Sampling prior to the fires was conducted between May 2001 and June 2003, while post-burn
sampling was conducted between August 2006 and September 2007. We calculated the relative
abundance of carnivore species for each track transect and camera station, comparing pre-burn and
post-burn abundance indices.
Fifteen medium to large mammal species were detected across Santa Ysabel and Rancho
Jamul at track transects and camera stations. We detected 11 native species including mountain lion
(Puma concolor), mule deer (Odocoileus hemionus), coyote (Canis latrans), bobcat (Felis rufus),
badger (Taxidea taxus), gray fox (Urocyon cinereoargenteus), raccoon (Procyon lotor), striped
skunk (Mephitis mephitis), spotted skunk (Spilogale gracilis), opossum (Didelphis virginiana), and
long-tailed weasel (Mustela frenata). We also detected four species typically associated with humans
including, domestic cow (Bos taurus), domestic horse (Equus caballus), domestic dog (Canis
familiaris), and domestic cat (Felis catus). Ten of the native species (badger excluded) and two
human-associated species (domestic horse and domestic dog) were documented within both study
sites.
Within Santa Ysabel and Rancho Jamul, we found little evidence that the 2003 wildfires
affected the relative abundance of the carnivore species for which we gathered sufficient data. Most
of the species we studied seemed capable of persisting in the patchwork of unburned and burned
habitats resulting from these wildfires. In addition, the effects of the fires were likely short term for
most carnivore species. We did not begin post-burn monitoring until nearly three years after the
wildfires of 2003, by which time we likely missed the more dramatic immediate responses to
wildfire. Overall, we suspect the indirect effects of wildfires, such as changes in habitat suitability
and predator-prey dynamics, were largely responsible for the mi
This mountain lion (Puma concolor; puma, cougar) study is headed by Dr. Winston Vickers of the Wildlife
Health Center at UC Davis (WHC). Dr. Fernando Nájera joined the UC Davis Wildlife Health Center as
co-Director of Carnivore Projects in March 2023. David Garcelon of the Institute for Wildlife Studies
(IWS) is the PI for the northeastern California part of the study, and Dr. Jessica Sanchez of the San Diego
Zoo Wildlife Alliance was a key contributor to several study elements in Southern California. Dr.’s
Vickers and Nájera prepared this report with contributions from the other project collaborators.
Overall activities and research into mountain lions by the UC Davis WHC have been ongoing since the
first capture of a mountain lion in the study in March of 2001. Over the course of this long-term study,
cougars were captured, sampled, and GPS collared in Orange, Riverside, San Diego, Modoc, Lassen, and
Kern Counties, with some of the most recent captures in the Gabilan Range and Pacheco Pass either in or
in close proximity to (Santa Clara and San Benito Counties) (Figure 2). Tissue samples have been obtained in the past from deceased animals in San Bernardino County, but no
captures have occurred there. Activities of both types are anticipated in additional counties in the future.
The study in southern California (Figure 3) has incorporated mountainous areas including the Santa Ana
Mountains (SAM) portion of the Peninsular Ranges (west of I-15) and the eastern Peninsular Mountain
Ranges (ePR) east of I-15 (Figure 3), and has been conducted under the authorization of the California
Department of Fish and Wildlife (CDFW) via a number of Memoranda of Understanding and Scientific
Collecting Permits. In 2016, an amendment to our SCP was approved to allow expansion of the study scope and region to
study of cougar ecology and interactions with pronghorn antelope (Antilocapra americana) in the
northeastern corner of California (Modoc, Lassen, and Siskiyou Counties) (Figure 4). This second part
of our study is being conducted in collaboration with, and with the financial support of, Dave Garcelon
and the Institute for Wildlife Studies (IWS). The first capture in that study area was in February of 2016.
A new 3-year Scientific Collecting Permit was approved in early 2022 that allowed further expansion of
the study areas to the Tehachapi Mountain Range north of Los Angeles (Figures 5 and 6) and the
Gabilan Range (Figure 7)
The focus of this study was on regional habitat linkage monitoring locations for tracking
corridor use by large mammals (i.e., deer, coyote, bobcat, mountain lion) as part of the
MSCP biological monitoring program. CBI identified chokepoints within linkages that serve as regional movement corridors for large mammals, both within the MSCP preserve system and to other NCCP subregions.
The MSCP preserve was designed to maintain connections between core habitat areas, including linkages between coastal lagoons and more inland habitats, and linkages between different watersheds. In addition to allowing for demographic and genetic exchange by all species between core preserve areas, linkages are intended to allow larger predators (mountain lions, coyotes, and bobcats) to move among conserved habitat blocks and reach coastal habitats.
This study was designed to address the following questions:
• Are the wildlife corridors identified in the subarea plans functional?
• What large mammals (deer, mountain lion, bobcat, coyote) and mesopredators
use the linkages?
• What potential constraints to animal movement exist in these areas?
• Where are habitat restoration or other management actions needed to facilitate
animal movement?
• Does the Scripps-Poway Parkway underpass function effectively for wildlife
movement?
• What survey methods are most efficient in identifying corridor use and
evaluating corridor function for each target species?
Badgers (Taxidea taxus) are wide-ranging mid-sized predators that are known to inhabit San
Diego County. Similar to the mountain lion, they are known to range over wide areas, often
making movements of 10km or more per day (Messick and Hornocker 1981; Hoodicoff 2003;
Minta 1993; Quinn 2008; Doyle et al. 2019). Therefore, they are a suitable focal species for
monitoring regional-scale connectivity. Unlike mountain lions that prefer to move within riparian
areas (Dickson et al. 2005), badgers prefer open or grassy areas and thus are likely better
indicators for upland connectivity and represent a different suite of species (Quinn 2008).
Badgers are a covered species under the San Diego Multiple Species Conservation Plan (MSCP)
(SDMMP 2011, 2017) and have been identified by the San Diego Monitoring and Management
Program (SDMMP) Connectivity Monitoring Strategic Plan (2011) as a target species for
monitoring regional-scale functional connectivity of upland and grassland habitats as well as a
species considered to be at risk of loss from the SDMMP Management Strategic Plan Area
(MSPA; SDMMP and Nature Conservancy 2017). The U.S. Geological Survey has been
studying badger distribution and activity in San Diego County since 2011 using a variety of
methods to better understand their distribution and core use areas (Brehme et al. 2012, 2015,
2016). The purpose of this report is to synthesize the techniques used and findings from the
Brehme et al. (2012, 2015, 2016) reports into one document as well as review the objectives and
methods for potential future research on the status and trends of this highly sensitive and elusive
species.
Roads can cause significant mortality for wildlife, but large roads like freeways can also form major barriers to wildlife movement and gene flow. Freeways are ubiquitous in southern California, and two freeways, Interstate 15 and U.S. 101, have been found to be barriers to wildlife passage and gene exchange, especially for mountain lions, between the Santa Ana Mountains and the Palomar Mountains and other mountains to the east (separated by Interstate 15), and between the Santa Monica Mountains and the Simi Hills, Santa Susana Mountains, and others to the north (separated by the 101 Freeway). We used two sources of information with the goal of bridging the gap between connectivity science and conservation practice. In early 2015 we engaged an independent panel of connectivity experts to evaluate possible locations and concepts for wildlife crossings along stretches of both freeways. We also developed and implemented an evaluation tool based on landscape characteristics and wildlife data to help prioritize locations for wildlife crossing infrastructure. The experts were asked to evaluate stretches of each freeway where wildlife studies have indicated that some connectivity potential remains due to the presence of natural habitat on both sides of the road, but where new or enhanced structures are likely required to restore lost connectivity. Multiple specific sites were examined along these stretches of each freeway. For I-15, both the Landscape and Expert scoring indicated that retention and enhancement of function under the Temecula Creek Bridge, and construction of a new under or overpass south of the bridge, were both likely needed for long term connectivity. For the 101 Freeway, the Landscape and Expert scoring both strongly concluded that West Liberty Canyon is the best location for a new wildlife crossing structure, with several other locations being sites where enhancements or new construction could serve the role of providing secondary crossings. The experts indicated that an overpass, over both 101 and the parallel Agoura Rd, was the best option here to provide connectivity for a range of species. The experts agreed that accompanying measures, such as effective wildlife fencing to funnel animals to crossing points and appropriate vegetative cover on and near structures were also important. They also recommended that, over the long term, more than one crossing structure should be enhanced or created for each linkage to assure sufficient movement of
