Region 6 Mammals Documents

2023-2024 Alpine Mesocarnivore Study Progress Report

Thu, 20 Nov 2025 11:02:33 -0800

Alpine Mesocarnivore Study 2023-2024 - Since 2016, the Bishop Field Office of the California Department of Fish and Wildlife (CDFW) has conducted annual surveys for mesocarnivores in upper elevations of the Sierra Nevada south and east of Yosemite National Park. The impetus for these surveys is to improve our understanding of mesocarnivore distribution and occupancy in alpine environments where these animals have rarely been studied, and in a region of California where the population status of many species is unknown. As managers discuss recovery of endangered species like Sierra Nevada red foxes (Vulpes vulpes necator; SNRF) and wolverines (Gulo gulo), information about the contemporary distribution of these species, as well as the distribution of other sympatric carnivore species, is critical to informing conservation planning. Each winter, we systematically deploy remote cameras at elevations above 3,000 m within a focal region such as a drainage basin, divide, or subrange. Surveys are designed to detect multiple mesocarnivore species; of particular interest are detections of rare, threatened, or endangered species like SNRF and wolverines. When cameras detect species of interest, we follow up with ground surveys to collect scats for genetic identification. We also maintain monitoring cameras in areas with prior detections of target species and deploy cameras opportunistically in locations where habitat is suitable and year-round access is logistically feasible. Over a study period of approximately 10 years (2016-2025), we will estimate the distribution and occupancy of numerous mesocarnivore species throughout the study area.

2014-2022 Long-term Mule Deer Population Monitoring in the Eastern Sierra

Tue, 18 Jun 2024 11:03:55 -0700

Long-term Mule Deer Population Monitoring in the Eastern Sierra - This report summarizes a long-term multiple data source mule deer monitoring project in the eastern Sierra Nevada conducted during 2014-2022. Our approach to deer herd management and conservation incorporates hybrid monitoring and provides more precise population estimates and the ability to detect changes in the deer population trajectory over time. Results of this project provide natural resource managers and decision-makers with the information necessary to responsibly evaluate the potential effects of various management decisions as they relate to the viability of eastern Sierra mule deer populations. During 2014-2022, we captured a total of 1,207 female mule deer in six herds in the eastern Sierra. Most animals were fitted with a colored VHF or GPS collar to assist in marking the animals for mark-resight population estimates and determining cause-specific mortality. Annual survival was low within the six deer herds; estimates of annual female survival ranged from 0.55-0.90 (mean was 0.75 for all years and herds). Consistent with low survival rates, population estimates suggested population declines for herds in which multiple surveys were completed. For all mortalities, cause of death was not able to be determined 64% (452/705) of the time. The primary known cause of death was mountain lion predation (69%, n=174), followed by vehicle collision (19%, n=47). Nutritional condition was quantified during captures in each herd annually and provided a measure of nutritional status and proximity to nutritional carrying capacity. Average body fat in females during spring captures was generally low in most years and herds (mean was 4.66% for all years, IFBFat scaled), which is also predictive of declining populations based on previous studies.

Alpine Mesocarnivore Study 2021-2022 Progress Report

Wed, 15 May 2024 13:02:53 -0700

Alpine Mesocarnivore Study 2021-2022 - Since 2016, the Bishop Field Office of the California Department of Fish and Wildlife (CDFW) has conducted annual surveys for mesocarnivores in upper elevations of the Sierra Nevada south of Yosemite National Park. The goal of these surveys is to improve our understanding of mesocarnivore distribution and occupancy in alpine environments where these animals have rarely been studied, and in a region of California where the population status of many species is unknown. As managers begin to discuss the potential risks and benefits of reintroducing SNRF and wolverines into their historical habitat in the Sierra Nevada, information about the contemporary distribution of these species, as well as the distribution of other carnivore species, will be critical to informing conservation planning. Each winter, we systematically deploy remote cameras at elevations above 3,050 m within a focal region such as a drainage basin, divide, or subrange. Surveys are designed to detect multiple mesocarnivore species; of particular interest are detections of rare, threatened, or endangered species like Sierra Nevada red foxes (Vulpes vulpes necator; SNRF) and wolverines (Gulo gulo). When cameras detect species of interest, we follow up with ground surveys to collect scats for genetic identification. We also maintain monitoring cameras in areas with prior detections of target species and deploy cameras opportunistically in locations where habitat is suitable and year-round access is logistically feasible. Over a study period of approximately 10 years (2016-2025), we will estimate the distribution and occupancy of numerous mesocarnivore species throughout the study area. During the 2021 survey season we surveyed the Goddard Divide study area, a region of Kings Canyon National Park and the Inyo and Sierra National Forests west of the town of Big Pine, California. We detected SNRF at one site at 3,321 m in November 2020. Other notable detections because of their occurrence at unusually high elevations were a gray fox (Urocyon cinereoargenteus) at 3,647 m in October 2020, a ringtail (Bassariscus astutus) at 3,255 m in October 2020, and a fisher (Pekania pennanti) at 3,376 m in April 2021. We did not detect wolverines. During the 2022 survey season we surveyed the Cirque Crest study area, a region of Kings Canyon National Park and the Inyo National Forest between Bishop Pass and Taboose Pass. We detected SNRF on five occasions at three sites. These detections represent the first confirmed SNRF in Kings Canyon National Park since the 1930s. There were no other notable carnivore detections during this survey. We did not detect wolverines.

Peninsular Bighorn Sheep 2020-21 Annual Report

Wed, 29 Nov 2023 11:59:52 -0800

California Department of Fish and Wildlife Peninsular Bighorn Sheep Annual Report 1 June 2020 - 31 May 2021 - Peninsular bighorn sheep (Ovis canadensis nelsoni) inhabit the desert slopes of the Peninsular Ranges of southern California and extend into the mountains of Baja California in Mexico. The population within the Peninsular Ranges was listed as threatened in 1971 under the California Endangered Species Act. In 1974, the population was estimated at 1,171 (Weaver 1975) but by 1996 the range-wide population estimate had declined to only 277 adult bighorn sheep (USFWS 2000). Peninsular bighorn sheep (PBS) were listed by the U.S. Fish and Wildlife Service (USFWS) as a federally endangered population segment in 1998 (63 FR 13134). Reasons for this listing were: 1) habitat fragmentation, degradation, and habitat loss caused by urban and commercial development; 2) disease; 3) predation coinciding with low population numbers; 4) human disturbance; 5) insufficient lamb recruitment; 6) invasive and toxic nonnative plants; and 7) prolonged drought (USFWS 2000). Sustainable management and conservation of PBS hinges on reliable and consistent population estimates. Unfortunately, the current population status of PBS is unknown. The last range-wide population survey, conducted in 2016, estimated a stable population of 884 Peninsular bighorn sheep. Population surveys were not conducted in 2018 or 2020 due to lack of helicopter availability and/or funding limitations. Therefore, it is unknown whether the range-wide population has remained stable, increased, or decreased since the 2016 surveys. Scientifically based population surveys are costly and without a dedicated funding source it will not be possible to determine if recovery goals are being met. Maintaining a representative sample of 25% to 30% radio-collared bighorn sheep in each recovery region is important for generating reliable mark-resight population estimates and accurately tracking trends in distribution and movement patterns, adult survivorship, cause-specific mortality, and overall health status. Unfortunately, due to on-going funding shortages, only 13% of the estimated range-wide ewe (female) population was radio-collared at the beginning of the current reporting period (June 1, 2020 - May 31, 2021) and 18% at the end of the reporting period (based on 2016 generalized ewe population survey estimate of 552). Therefore, all descriptive statistics presented for the current reporting period may not fully represent the greater PBS population. Consistent funding for every recovery region is needed before information on population status and dynamics can be accurately assessed.

Peninsular Bighorn Sheep 2019-20 Annual Report

Wed, 29 Nov 2023 11:59:13 -0800

California Department of Fish and Wildlife Peninsular Bighorn Sheep 2019-20 Annual Report - Desert bighorn sheep (Ovis canadensis nelsoni) inhabit the desert slopes of the Peninsular Ranges of southern California and extend into the mountains of Baja California in Mexico. The population within the Peninsular Ranges was listed as threatened in 1971 under the California Endangered Species Act. In 1974, the population was estimated at 1,171 (Weaver 1975) but by 1996 the range-wide population estimate had declined to only 277 adult sheep (USFWS 2000). Peninsular bighorn sheep were listed by the U.S. Fish and Wildlife Service as a federally endangered population segment in 1998 (63 FR 13134). Reasons for this listing were: 1) habitat fragmentation, degradation, and habitat loss by urban and commercial development; 2) disease; 3) predation coinciding with low population numbers; 4) human disturbance; 5) insufficient lamb recruitment; 6) nonnative toxic plants; and 7) prolonged drought (USFWS 2000). The last range-wide population survey, conducted in 2016, estimated a stable population of 884 Peninsular bighorn sheep. The current population status of Peninsular bighorn sheep is unknown because surveys were not conducted in 2018 due to lack of helicopter availability and/or funding limitations. Therefore, it is unknown whether the range-wide population has remained stable, increased, or decreased since the 2016 surveys. Maintaining a representative sample of 25% to 30% radio-collared bighorn sheep in each recovery region is important for generating reliable mark-resight population estimates and accurately tracking trends in distribution and movement patterns, adult survivorship, cause-specific mortality, and overall health status. Unfortunately, due to on-going funding shortages, only 16% of the estimated range-wide ewe (female) population was radio-collared at the beginning of the current reporting period compared to only 13% at the end of the reporting period (based on 2016 generalized ewe population survey estimate of 552). Therefore, all descriptive statistics presented for the current reporting period may not necessarily be representative of the greater Peninsular bighorn sheep population. By 2021, the following recovery regions will have little to no radio-collared bighorn sheep representation: Coyote Canyon, Northern and Southern San Ysidro Mountains, and the Southern Santa Rosa Mountains. Consistent funding for every recovery region is needed before information on population status and dynamics can be accurately assessed. On average, 12.8% of all active radio-collared bighorn sheep die each year with predation accounting for 7.5%, unknown causes 2.5%, nonpredation 1.8%, capture related 0.6%, and urban related 0.4%. Over the current reporting period, 14.1% of all active radio-collared bighorn sheep died of which 10.9% was attributed to predation, 2.2% was due to unknown causes, and 1.1% was due to nonpredation.

Peninsular Bighorn Sheep Subpopulation Recovery Regions

Mon, 17 Apr 2023 09:26:57 -0700

Peninsular Bighorn Sheep Subpopulation Recovery Regions - Peninsular Bighorn Sheep Subpopulation Recovery Regions Recovery Regions 1. San Jacinto Mountains 2. Northern Santa Rosa Mountains 3. Central Santa Rosa Mountains 4. Southern Santa Rosa Mountains 5. Coyote 6. North San Ysidro Mountains 7. South San Ysidro Mountains 8. Vallecitos 9. Carrizo

Peninsular Bighorn Sheep 2018-19 Annual Report and Recovery Program Review 1992 - 2019

Mon, 17 Apr 2023 09:26:47 -0700

Peninsular Bighorn Sheep 2018-19 Annual Report and Recovery Program Review 1992 - 2019 - Peninsular bighorn sheep (Ovis canadensis nelsoni) inhabiting the Peninsular Ranges of southern California are a federally listed endangered species. The California Department of Fish and Wildlife (CDFW) carries out population monitoring and recovery under U.S. Fish and Wildlife Service (USFWS) Endangered Species Permit TE163017-1. This report summarizes peninsular bighorn sheep (PBS) radio-collar monitoring, disease surveillance, and cause-specific mortality investigations undertaken by CDFW from 1 June 2018 to 31 May 2019. In addition, PBS data collected by CDFW over the past 27 years is reviewed.

Distribution and Abundance of Tule Elk in the Owens Valley

Mon, 17 Apr 2023 09:24:30 -0700

Tule Elk in the Owens Valley, abundance and home range - In 2019, the minimum count for the Owens Valley population of tule elk (Cervus canadensis nannodes) was 343 elk with an annual recruitment rate of 0.37; the historic average annual population and recruitment rate were 335 and 0.30, respectively. The Owens Valley population of tule elk is distributed between lowland habitat, concentrated mainly around the Owens River and east of U.S. Highway 395, and upland habitat, which is located on the west side of Highway 395 along the base of the Sierra Nevada mountains. The lowland population is comprised of the Bishop, Tinemaha, Independence, and Lone Pine sub-herds with a current population of 196 tule elk. The upland population is comprised of the Tinemaha West, Tinemaha Mountain, Goodale, and Whitney sub-herds with a current population of 147 tule elk. There are no known cow elk occupying the Tinemaha Mountain sub-herd at present.

2015-2018 Alpine Mesocarnivore Study Progress Report

Mon, 17 Apr 2023 08:48:02 -0700

New Detections of the Sierra Nevada Red Fox - We present preliminary findings of a study initiated in 2015 by the California Department of Fish and Wildlife’s Bishop Field Office (CDFW) to investigate the distribution of alpine mesocarnivores in the Sierra Nevada south of Yosemite National Park (Figure 1). Using noninvasive remote camera and scat surveys during 2015-18, we detected 12 bird species, 2 ungulate species, 8 rodent species, 2 lagomorph species, and 11 carnivore species, including the Sierra Nevada red fox (SNRF). Notably, we did not detect wolverines. The SNRF once ranged throughout the alpine and subalpine habitats of the Sierra Nevada and Cascades in California and Oregon. Today, the subspecies likely occupies only portions of its historical range, and is currently state-listed as threatened in California and proposed for federal listing as endangered by the U.S. Fish and Wildlife Service. In 2018, we documented three SNRF individuals in the Mono Creek watershed south of Mammoth Lakes, California. Genetic analysis of scat samples verified that the individuals assign most closely to the historical SNRF population, making these the southernmost confirmed SNRF in nearly 100 years. One of the individuals, a male, was last sampled in September 2017 near Sonora Pass, demonstrating a dispersal of more than 120 km within eight months. The other two individuals, females, had not been detected previously. Future camera and scat surveys will focus on characterizing the abundance and distribution of SNRF in Mono Creek, while also expanding surveys into unsampled areas of the Sierra Nevada south of Yosemite National Park, including in Sequoia and Kings Canyon National Parks. Efforts are currently underway to prepare a Conservation Strategy for the SNRF; our survey results will help to inform this document’s research and management recommendations to conserve the subspecies. In addition, we will continue to investigate the distribution in high elevation habitats of other mesocarnivore species of interest, including wolverines, coyotes, martens, gray foxes, and kit foxes.

Peninsular Bighorn Sheep 2017-18 Annual Report

Mon, 17 Apr 2023 01:22:04 -0700

2017-18 Annual Report Peninsular Bighorn Sheep - Desert bighorn sheep (Ovis canadensis nelsoni) inhabit the desert slopes of the Peninsular Ranges of southern California and extend into the mountains of Baja California in Mexico. The population within the Peninsular Ranges was listed as threatened in 1971 under the California Endangered Species Act. In 1974, the population was estimated at 1,171 (Weaver 1975) but by 1996 the rangewide population estimate had declined to only 276 adult sheep (USFWS 2000). In 1998, the U.S. Fish and Wildlife Service (USFWS) listed Peninsular bighorn sheep as a federally endangered population segment (63 FR 13134). Reasons for this listing were: 1) habitat fragmentation, degradation, and habitat loss by urban and commercial development, 2) disease, 3) predation coinciding with low population numbers, 4) human disturbance, 5) insufficient lamb recruitment, 6) nonnative toxic plants, and 7) prolonged drought (USFWS 2000). The California Department of Fish and Wildlife (CDFW) carry out population recovery under USFWS Endangered Species Recovery Permit TE163017-1. Presently, the population of desert bighorn sheep in the Peninsular Ranges is stable based on the 2016 CDFW survey estimate of 884 adult bighorn sheep. The range-wide ewe (female sheep) population estimate was 552 with greater than 25 ewes within each of the 9 recovery regions. As such, 2016 marked year 1 of 6 in meeting criterion 1 in section II.B.2 for downlisting Peninsular bighorn sheep from endangered to threatened status (USFWS 2000). This report covers a 12-month period from 1 June 2017 to 31 May 2018 and summarizes data collected from 9 recovery regions within the Peninsular Ranges. The 9 recovery regions are: 1) San Jacinto Mountains (SJM), 2) Northern Santa Rosa Mountains (NSRM), 3) Central Santa Rosa Mountains (CSRM), 4) Southern Santa Rosa Mountains (SSRM), 5) Coyote Canyon (CoC), 6) Northern San Ysidro Mountains (NSYM), 7) Southern San Ysidro Mountains (SSYM), 8) Vallecito Mountains (VM), and 9) Carrizo Canyon (CC). In order to obtain accurate estimates of ewe abundance.

Peninsular Bighorn Sheep 2016-17 Annual Report

Sun, 16 Apr 2023 18:30:02 -0700

2016-17 Annual Report Peninsular Bighorn Sheep - Desert bighorn sheep (Ovis canadensis nelsoni) inhabit the desert slopes of the Peninsular Ranges of southern California and extend into the mountains of Baja California in Mexico. The population within the Peninsular Ranges was listed as threatened in 1971 under the California Endangered Species Act. In 1974, the population was estimated at 1,171 (Weaver 1975) but by 1996 the rangewide population estimate had declined to only 276 adult sheep (USFWS 2000). Peninsular bighorn sheep were listed by the U.S. Fish and Wildlife Service (USFWS) as a federally endangered population segment in 1998 (63 FR 13134). Reasons for this listing were: 1) habitat fragmentation, degradation, and habitat loss by urban and commercial development; 2) disease; 3) redation coinciding with low population numbers; 4) human disturbance; 5)insufficient lamb recruitment; 6) nonnative toxic plants; and 7) prolonged drought (USFWS 2000). The California Department of Fish and Wildlife (CDFW) carries out population recovery under USFWS Endangered Species Recovery Permit TE163017-1. Presently, the population of desert bighorn sheep in the Peninsular Ranges is stable based on the 2016 CDFW survey estimate of 884 adult bighorn sheep. The range-wide female population estimate was 552 with greater than 25 adult female bighorn sheep within each of the 9 recovery regions. As such, 2016 marked year 1 of 6 in meeting criterion 1 in section II.B.2 for downlisting peninsular bighorn sheep from endangered to threatened status (USFWS 2000).

West Walker Deer Herd Study Final Report

Sun, 16 Apr 2023 17:51:56 -0700

West Walker Deer Herd Study Final Report - From May 1992-June 1995, 1 used radio-telemetry to determine the seasonal movement and migration patterns of mule deer (Odocoileus hemionus hemionus) from the West Walker (WW) herd. We captured 133 deer and attached radio transmitters to 47 adult females and 10 adult males. Ninety-seven percent of radio-collared deer were migratory with distinct summer and winter ranges. Linear distances traveled between winter and summer range centers of activity (COA’s) varied from 5.7 to 71.3 km. Changes in elevation between winter and summer ranges varied from +550 to +1,425 m. Timing of spring migration from the winter range varied annually by as much as 1 month during the study and was related to winter severity and cool spring temperatures. Deer made extensive use of holding areas during spring migration; the period of delay averaged 20 days following mild winters and 35 days following severe winters. Deer occupied approximately 2,450 km2 of summer range located on both the east and west slopes of the Sierra Nevada. Sixty-four percent of radio-collared deer summered on east slope summer ranges and 36% summered on west slope summer ranges. Deer showed poor fidelity to consecutive summer range COA’s. Distances separating summer range COA’s of females monitored for > two successive years averaged 1.6 km. Timing of fall migration from the summer range varied by as much as two weeks and was related to the severity of fall weather. Deer showed poor fidelity to early winter (NovemberJanuary) COA’s. Distances separating early winter COA’s of adult females monitored for > two successive years averaged 4.7 km. Deer showed stronger fidelity to late winter (February-April) COA’s. Distances separating late winter COA’s of females monitored for > 2 successive years averaged 1.8 km. This study revealed that deer from a relatively small area of winter range (800 km2) inhabited a large geographical area of summer range (2,450 km2) on both the east and west slopes of the central Sierra Nevada. This study also revealed that WW deer shared summer range with Rocky Mountain mule deer from two other eastern Sierra Nevada herds and California mule deer (O. h. californicus) from at least three western Sierra Nevada herds. Therefore, habitat management programs designed to increase deer productivity in the WW herd should be conducted on primary winter range sites when deer are concentrated and can be managed on a herd-specific basis. Similarly, any reduction in the amount of area available on primary winter ranges due to habitat loss, human disturbance or other factors, could have broad implications in the occurrence of deer summering over a large portion of central Sierra Nevada.

Migration and Seasonal Habitats of the Casa Diablo Deer Herd

Sun, 16 Apr 2023 17:51:28 -0700

Migration and Seasonal Habitats of the Casa Diablo Deer Herd - One hundred and seventeen mule deer, Qdocoileus hemionus hemionus, were captured on wintering areas from January-March 1986 and January-March 1987. Twenty-seven females and 1 adult male were radio-collared and monitored for two spring and two fall migrations in order to delineate migration routes and seasonal ranges. Timing of spring migration was similar during both years despite extremes in severity of winters. Two radio-collared does utilized different spring migration routes and wintering areas in consecutive years. Timing of fall migration was correlated with snowfall in 1987, but not in 1986. Deer remained on holding areas and delayed migration for up to 6 weeks during both spring and fall. Fifteen radio—collared deer occupied summer range on the east slope of the Sierra Nevada; 14 of these utilized aspen riparian habitats. Three radio—collared does crossed the Sierra crest to west side summer ranges. Those radio-collared does occupying summer range in Jeffrey pine (Pinus jeffreyi) habitat had larger home ranges than those in more diverse areas. All radio-collared deer exhibited strong fidelity to summer home ranges. Water was found to be the factor most limiting deer distribution and densities throughout portions of winter and summer ranges.

Ecology and Productivity of Two Interstate Deer Herds in the Eastern Sierra Nevada

Sun, 16 Apr 2023 17:51:13 -0700

Ecology and Productivity of Two Interstate Deer Herds in the Eastern Sierra Nevada - Rocky Mountain mule deer (Odocoi1eus hemionus hemionus) from two interstate deer herds, the East Walker (EW) and Mono Lake (ML) herds, were studied from January -1988-June 1991 under contract with the California Department of Fish and Game (DFG). A total of 162 animals were captured and marked; 61 were fitted with radio-telemetry collars for monitoring of movements. Radio-collared deer were located a total of 3872 times from March 1988-June 1991. Deer leave western Nevada winter ranges in late March and early April and move to holding areas located at intermediate elevations along the east slope of the Sierra Nevada mountains in eastern California. There was a significant year-by-herd difference in the timing of spring migration from the winter range. Deer from the EW herd delayed spring migration on irrigated pasture lands located on secondary winter range adjacent to the East Walker River. Mean straight line distances between winter and summer ranges of EW and ML deer were 35 and 65 km,respectively. Deer displayed strong fidelity to individual summer and winter ranges; only one radio-equipped doe used more than a single summer home range during the study. Marked deer from different winter ranges were found to occupy summer ranges of close proximity. Conversely, marked deer from the same winter range were found to disperse to opposite ends of the summer range. Summer home range size of adult does averaged 21.4 ha. There was a significant difference (P <_ 0.025) in the summer home range sizes of adult does which occupied grazed versus ungrazed habitats. The average size of summer home ranges grazed by livestock was 2.5 times larger (25.87 ha) than those that were not grazed (10.23 ha). The summer home ranges of 38 randomly selected adult does were examined by the investigator; 33 (87%) were grazed by livestock to varying intensities.

Snow Creek Ski Area Deer Survey 1995 Spring and Fall Migration Study

Sun, 16 Apr 2023 17:50:41 -0700

Snow Creek Ski Area Deer Survey 1995 Spring and Fall Migration Study - In June 1994, Dempsey Construction Corporation (DCC) of Mammoth Lakes, California, completed preparation of a Deer Herd Monitoring Plan (DHMP) (Raedeke Associates 1994) for the proposed Snowcreek Ski Area (SSA). The Final Environmental Impact Statement (FEIS) for the SSA specified that the DHMP be developed in order to assess the effectiveness of mitigation measures designed to minimize impacts of the SSA on migratory mule deer, and to determine the overall effect of the SSA development on the Round Valley deer herd, formerly known as the Sherwin Grade and Buttermilk deer herds. The SSA is located immediately south of the Town of Mammoth Lakes (TML) on approximately 3,100 acres of public land managed by the U.S. Forest Service (USFS). The proposed ski area and surrounding vicinity is regarded as important transition range for mule deer (Odocoileus hemionus hemionus) from the Round Valley herd, which migrate through the area during annual spring and fall migrations. Over the past decade, the California Department of Fish and Game (CDFG) has been collecting data on the Round Valley deer population with emphasis on factors affecting population size and trend and habitat use relationships. During the same period, DCC has collected site-specific data on the timing and locations of deer use patterns in the proposed SSA permit area and surrounding vicinity. The DHMP was designed to expand on this existing information and to furnish data required by the SSA-FEIS for the analysis of potential impacts to migratory mule deer (Raedeke Associates 1994). This report summarizes field studies completed by DCC during the 1995 spring and fall migrations. Specific objectives of the spring work were to: 1) determine, through the use of radio telemetry and infrared sensor equipment, the amount, timing, and specific locations of migratory deer use in the SSA permit area and surrounding vicinity; 2) estimate deer population size on the Sherwin Holding Area (SHA) from mark-recapture techniques; 3) develop a “sightablity index” to estimate the number of deer in the holding area based on the number of deer observed during a given census; 4) determine patterns of diurnal habitat use by radio-collared deer on the SHA, SSA permit area, and surrounding lands; and 5) delineate specific migratory routes over the Sierra Crest used by individual radio-collared deer. Objectives of the fall work were to determine the timing and intensity of fall migration through the SSA permit area and the specific locations of deer migration routes.

Condition and Reproductive Performance of Female Mule Deer in the Central Sierra Nevada

Sun, 16 Apr 2023 17:50:37 -0700

Condition and Reproductive Performance of Female Mule Deer in the Central Sierra Nevada - I determined reproductive performance in relation to age and physical condition of 58 female Rocky Mountain mule deer, Odocoileus hemionus hemionus,collected from the West Walker winter range in northern Mono County, California, and southwestern Douglas County, Nevada during March 1993 and March 1994. Among adult females, pregnancy and fetal rates were 86% and 1.52 fetuses/female in 1993 and 88% and 1.56 fetuses/female in 1994. Bled carcass weights, eviscerated carcass weights, and kidney fat indices of adult females were greater in 1994,indicating that deer were in better condition than in 1993. Litter category was not related to age or female body condition. The overall sex ratio of fetuses was 107 males:100 females. Reproductive potential in the West Walker deer herd was comparable to that reported for other nutritionally stressed mule deer populations.My study suggested that low productivity was in response to drought-induced changes in habitat quality.

Eastern Sierra Nevada Bobcat Study Annual Report 2016

Sun, 16 Apr 2023 17:35:11 -0700

Eastern Sierra Nevada Bobcat Study Annual Report - A study plan titled “Eastern Sierra Nevada Bobcat Study” initiated a population survey and GPS collar study in the fall of 2014 to learn more about Eastern Sierra bobcat (Lynx rufus) densities and population characteristics. This year is the second year of the study which was designed to better monitor and manage low elevation (<9,000 ft) bobcat populations in Inyo and Mono Counties. The main objective of this study was initially to standardize survey techniques for bobcats that would allow the Department of Fish and Wildlife (Department) to monitor abundance of bobcats. This study was initiated in response to the proposed statewide ban on bobcat trapping in spring of 2014.

Peninsular Bighorn Sheep Recovery 2014 Annual Report

Sun, 16 Apr 2023 16:22:08 -0700

2014 Annual report peninsular bighorn sheep - Presently, the population of desert bighorn sheep (Ovis canadensis nelsoni) in the Peninsular Ranges is considered to be stable to increasing based on the most recent 2010 California Department of Fish and Wildlife (CDFW) range-wide survey estimate of 955 bighorn sheep. At the beginning of 2014, the 9 recovery regions within the Peninsular Ranges contained a total of 56 (49 ewes & 7 rams) active radio-collared bighorn sheep. In the fall of 2014, an additional 50 bighorn sheep were radiocollared within 5 recovery regions. Throughout the year, there were 9 radio-collared bighorn sheep mortalities range-wide. Mortalities by recovery region were: Northern Santa Rosa Mountains = 2 ewes; Central Santa Rosa Mountains = 1 ewe; Southern Santa Rosa Mountains = 1 ewe; Vallecito Mountains = 1 ewe; and Carrizo Canyon = 4 (1 ewe & 3 rams). The average age of sheep that died was 9-years-old with a range between 5 and 14 years. At the close of 2014, there were a total of 95 (89 ewes & 6 rams) radio-collared bighorn sheep throughout the recovery regions. Estimating lamb survival range-wide is difficult due to the amount of intensive monitoring necessary. However, lamb survival rates in the recovery regions monitored are typically asynchronous among regions and years and have ranged between 0 and 70% with an average of 30% survival at 6 months. Anza-Borrego Desert State Park (ABDSP) conducts an annual waterhole count each summer in which lamb to ewe ratios are estimated for specific areas of 4 recovery regions; and, in 2014, the estimated lamb survival was 32%. CDFW has monitored lamb survival and recruitment within 2 to 5 recovery regions from 2008 to 2014 and has found varying degrees of pneumonia in all 5 recovery regions. Pneumonia in lambs has been of particular concern in the Northern San Ysidro Mountains; however, in 2014 lamb survival to 6 months was estimated at 45%; a vast improvement compared to the previous 6 years.

Peninsular Bighorn Sheep Recovery 2013 Annual Report

Sun, 16 Apr 2023 16:21:59 -0700

2013 Annual report peninsular bighorn sheep - This report highlights information collected by the California Department of Fish and Wildlife (CDFW) on bighorn sheep (Ovis canadensis nelsoni) capture and radiocollaring, cause specific mortality and survival, distribution and movement, and percentage of collared bighorn sheep in the Peninsular Mountain Ranges of southern California from 1 January 2013 through 31 December 2013. The Peninsular bighorn sheep population contains nine designated recovery regions occupying portions of western Riverside and Imperial Counties and eastern San Diego County (Figure 1). The 9 recovery regions are: 1) San Jacinto Mountains (SJM), 2) Northern Santa Rosa Mountains (NSRM), 3) Central Santa Rosa Mountains (CSRM), 4) Southern Santa Rosa Mountains (SSRM), 5) Coyote Canyon (CoC), 6) Northern San Ysidro Mountains (NSYM), 7) Southern San Ysidro Mountains (SSYM), 8) Vallecito Mountains (VM), and 9) Carrizo Canyon (CC).

Peninsular Bighorn Sheep Recovery 2012 Annual Report

Sun, 16 Apr 2023 16:21:56 -0700

2012 Annual report peninsular bighorn sheep - This report highlights information collected by the California Department of Fish and Wildlife (CDFW) on bighorn sheep (Ovis canadensis nelsoni) capture and radiocollaring, cause specific mortality and survival, distribution and movement, and percentage of collared bighorn sheep in the Peninsular Mountain Ranges of southern California from 1 January 2012 through 31 December 2012. The report also provides population estimates from 1994 – 2010 for 7 recovery regions, cause specific mortality and survival rates of collared females from 1993 – 2012 for 5 recovery regions, and lamb survival and recruitment from 2008 – 2012 for 4 recovery regions. A discussion of current recovery threats and management strategies in 7 recovery regions is also included. The Peninsular bighorn sheep population contains nine designated recovery regions occupying portions of western Riverside and Imperial Counties and eastern San Diego County (Figure 1). CDFW conducted monitoring activities in seven of nine recovery regions located east of Highway 74: Central Santa Rosa Mountains (CSRM), Southern Santa Rosa Mountains (SSRM), Coyote Canyon (CoC), Northern San Ysidro Mountains (NSYM), Southern San Ysidro Mountains (SSYM), Vallecito Mountains (VM), and Carrizo Canyon (CC). CDFW jointly monitored CSRM with the Bighorn Institute (BI), while the Northern Santa Rosa Mountains (NSRM) and San Jacinto Mountain (SJM) recovery regions located west of Highway 74 were monitored solely by BI.

Peninsular Bighorn Sheep Recovery 2011 Annual Report

Sun, 16 Apr 2023 16:21:54 -0700

2011 Annual report peninsular bighorn sheep - This report highlights information collected by the California Department of Fish and Game (CDFG) over the reporting period, 1 January 2011 through 31 December 2011 relating to bighorn sheep (Ovis Canadensis nelsoni) in the Peninsular mountain ranges of southern California. The Peninsular bighorn sheep population contains nine designated recovery regions occupying portions of western Riverside and Imperial Counties and eastern San Diego County (Figure 1). CDFG conducted monitoring activities in seven of nine recovery regions located east of Highway 74: Central Santa Rosa Mountains (CSRM), Southern Santa Rosa Mountains (SSRM), Coyote Canyon (CoC), North San Ysidro Mountains (NSYM), South San Ysidro Mountains (SSYM), Vallecito Mountains (VM), and Carrizo Canyon (CC). CDFG jointly monitored CSRM with the Bighorn Institute (BI), while the Northern Santa Rosa Mountains (NSRM) and San Jacinto Mountain (SJM) recovery regions located west of Highway 74 were monitored solely by BI.

Peninsular Bighorn Sheep Recovery 2010 Annual Report

Sun, 16 Apr 2023 16:21:50 -0700

2010 Annual report peninsular bighorn sheep - This report highlights information collected by the California Department of Fish and Game (CDFG) over the reporting period, 1 January 2010 through 31 December 2010 relating to bighorn sheep (Ovis canadensis) in the Peninsular mountain ranges of southern California. The Peninsular bighorn sheep population contains nine designated recovery regions occupying portions of western Riverside and Imperial Counties and eastern San Diego County. CDFG conducted monitoring activities in seven of the nine recovery regions located east of Highway 74 and conducted capture and population surveys in all nine recovery regions. CDFG conducted monitoring in the Central Santa Rosa Mountain (CSRM), Southern Santa Rosa Mountain (SSRM), Coyote Canyon (CoC), North San Ysidro Mountain (NSYM), South San Ysidro Mountain (SSYM), Vallecito Mountain (VM), and Carrizo Canyon (CC) recovery regions. CDFG jointly monitored CSRM with the Bighorn Institute (BI), while the Northern Santa Rosa Mountain (NSRM) and San Jacinto Mountain (SJM) recovery regions located west of Highway 74 were monitored solely by BI.

Peninsular Bighorn Sheep Recovery 2009 Annual Report

Sun, 16 Apr 2023 16:21:49 -0700

2009 Annual report peninsular bighorn sheep - This report highlights information collected by the California Department of Fish and Game (CDFG) over the reporting period, 1 January 2009 through 31 December 2009 relating to bighorn sheep (Ovis canadensis) in the Peninsular mountain ranges of southern California. The Peninsular bighorn sheep population contains nine designated recovery regions occupying portions of western Riverside and Imperial Counties and eastern San Diego County. CDFG conducted monitoring activities in seven of nine recovery regions located east of Highway 74: Central Santa Rosa Mountain (CSRM), Southern Santa Rosa Mountain (SSRM), Coyote Canyon (CoC), North San Ysidro Mountain (NSYM), South San Ysidro Mountain (SSYM), Vallecito Mountain (VM), and Carrizo Canyon (CC). CDFG jointly monitored CSRM with the Bighorn Institute (BI), while the Northern Santa Rosa Mountain (NSRM) and San Jacinto Mountain (SJM) recovery regions located west of Highway 74 were monitored solely by BI.

Map Showing Expanision Pinon Juniper Distribution in White Mountain Deer Habitat

Sun, 16 Apr 2023 15:39:13 -0700

Map Showing Expanision Pinon Juniper Distribution in White Mountain Deer Habitat - An attempt to quantify the extent of PJ expansion in the White Mountains in mule deer habiat

Zone X9A Deer Hunting Road Access Map - Southern Section

Sun, 16 Apr 2023 12:10:50 -0700

Zone X9A Deer Hunting Road Access Map - Southern Section - Road Access for Deer Hunting in the Southern part of Zone X9A

Zone X9A Deer Hunting Road Access Map - Central Section

Sun, 16 Apr 2023 12:10:49 -0700

Zone X9A Deer Hunting Road Access Map - Northern Section - Road Access for Deer Hunting in the Central part of Zone X9A

Zone X9A Deer Hunting Road Access Map - Northern Section

Sun, 16 Apr 2023 12:10:47 -0700

Zone X9A Deer Hunting Road Access Map - Northern Section - Road Access for Deer Hunting in the Northern part of Zone X9A

Flat Tailed Horned Lizard Distribution Map 2012

Sun, 16 Apr 2023 12:09:45 -0700

Flat Tailed Horned Lizard Distribution Map 2012 - Flat Tailed Horned Lizard Distribution Map 2012

2011 Wister Marsh Bird Survey Report

Sun, 16 Apr 2023 12:09:29 -0700

Yuma Clapper Rail , Least Bittern , and Virginia Rail Survey 2010 Wister Marsh - The 2011 marsh bird surveys of the Imperial Wildlife Area (IWA) were conducted by California Department of Fish and Game (DFG). The survey is based on Standardized North American Marsh Bird Protocol (SNAMBP). Black rail (Laterallus jamaicensis), least bittern (Ixobrychus exilis), Virginia rail (Rallus limicola), clapper rail (Rallus longirostris), common moorhen (Gallinula chloropus), American bittern (Botaurus lentiginosus), pied-billed grebe (Podilymbus podiceps) and sora (Porzana carolina) were recorded on the datasheets.

2010 Wister Marsh Bird Survey Report

Sun, 16 Apr 2023 12:09:26 -0700

Yuma Clapper Rail , Least Bittern , and Virginia Rail Survey 2010 Wister Marsh - The 2007 marsh bird surveys of the Imperial Wildlife Area (IWA) were conducted by California Department of Fish and Game (DFG). The survey is based on Standardized North American Marsh Bird Protocol (SNAMBP). Black rail (Laterallus jamaicensis), least bittern (Ixobrychus exilis), Virginia rail (Rallus limicola), clapper rail (Rallus longirostris), common moorhen (Gallinula chloropus), American bittern (Botaurus lentiginosus), pied-billed grebe (Podilymbus podiceps) and sora (Porzana carolina) were recorded on the datasheets.

2009 Wister Marsh Bird Survey Report

Sun, 16 Apr 2023 12:09:23 -0700

Yuma Clapper Rail Survey 2009 Wister Marsh - The 2009 marsh bird surveys of the Imperial Wildlife Area (IWA) were conducted by California Department of Fish and Game (DFG) Wildlife Techniciain Paula Whitten. The survey is based on Standardized North American Marsh Bird Protocol (SNAMBP).

2008 Wister Marsh Bird Survey Report

Sun, 16 Apr 2023 12:09:22 -0700

Yuma Clapper Rail Survey 2008 Wister Marsh - The 2008 marsh bird surveys of the Imperial Wildlife Area (IWA) were conducted by California Department of Fish and Game (DFG) Associate Wildlife Biologist Steve Gibson. The survey is based on Standardized North American Marsh Bird Protocol (SNAMBP).

2007 Wister Marsh Bird Survey Report

Sun, 16 Apr 2023 12:09:20 -0700

Yuma Clapper Rail Survey 2007 Wister Marsh - The 2007 marsh bird surveys of the Imperial Wildlife Area (IWA) were conducted by California Department of Fish and Game (DFG) Associate Wildlife Biologist Steve Gibson. The survey is based on Standardized North American Marsh Bird Protocol (SNAMBP).

2006 Wister Marsh Bird Survey Report

Sun, 16 Apr 2023 12:09:18 -0700

Yuma Clapper Rail Survey 2006 Wister Marsh - The 2006 marsh bird surveys of the Imperial Wildlife Area (IWA) were conducted by California Department of Fish and Game (DFG) Associate Wildlife Biologist Steve Gibson (myself). This is the first time the Standardized North American Marsh Bird Protocol (SNAMBP) has been used at the IWA. This new protocol will replace the Yuma Clapper Rail Survey Protocol from January, 2000, that has been conducted annually at IWA in the past. Multiple observers were not available for this survey. The same points sampled in previous years at the Wister Unit were used to conduct this survey. The points are set at 200 M intervals as per the Yuma Clapper Rail Survey Protocol (January, 2000). The SNAMBP suggests new stations be placed at 400 M intervals and no change to previously established sites. There were very few new stations added, and these were placed at an interval of 400 M. There were two survey areas consisting of the IWA Wister Unit and the Dos Palmas Preserve (DPP). This is the first time a Yuma Clapper Rail or SNAMBP has been conducted at DPP. Two complete surveys of each survey area were completed within the survey period.

2019-2020 Alpine Mesocarnivore Study Progress Report

Fri, 17 Mar 2023 11:48:26 -0700

Alpine Mesocarnivore Project - Since 2016, the Bishop Field Office of the California Department of Fish and Wildlife (CDFW) has conducted annual surveys for mesocarnivores in upper elevations of the Sierra Nevada south of Yosemite National Park. The impetus for these surveys is to improve our understanding of mesocarnivore distribution and occupancy in alpine environments where these animals have rarely been studied, and in a region of California where the population status of many species is unknown. Each winter, we deploy remote cameras at elevations above 2,700 m within a focal region such as a drainage basin, divide, or subrange. Surveys are designed to detect multiple mesocarnivore species; of particular interest are detections of rare, threatened, or endangered species like Sierra Nevada red foxes (Vulpes vulpes necator; SNRF) and wolverines (Gulo gulo luscus). When cameras detect species of interest, we follow up with ground surveys to collect scats for genetic identification. We also maintain monitoring cameras in areas with prior detections of target species, and deploy cameras opportunistically in locations where habitat is suitable and year-round access is logistically feasible. Over a study period of approximately 10 years (2016—2025), we will estimate the distribution and occupancy of numerous mesocarnivore species throughout the study area. During the 2019 survey season we surveyed the Ritter Range, a subrange of the Sierra Nevada south of Yosemite National Park and west of the town of Mammoth Lakes. We detected SNRFat two sites in the Ritter Range in May and June 2019. Other notable detections include a fisher (Pekania pennanti) at 3,294 m and a kit fox (Vulpes macrotis) at 3,303 m. We did not detect wolverines. During the 2020 survey season we surveyed the Silver Divide, a drainage divide southeast of Mammoth Lakes that separates the Fish Creek and Mono Creek watersheds. We did not detect SNRF or wolverines in this study area. The only unusual detection was a gray fox (Urocyon cinereoargenteus) at 3,393 m.

Desert Bighorn Sheep Status Report November 2013 to October 2016

Wed, 20 Nov 2019 14:49:45 -0800

A summary of desert bighorn sheep population monitoring and management by the California Department of Fish and Wildlife - Desert bighorn sheep (Ovis canadensis nelsoni) historically occupied more than 60 mountain ranges in California (Figure 1). This report documents data collection and management actions performed by California Department of Fish and Wildlife’s (CDFW) Bishop Field Office between November 1, 2013 and October 31, 2016. The Bishop Field Office monitors desert bighorn populations within Region 6. This includes the White Mountains in the north to Highway 62 in the south, the Nevada border in the east, and California’s Highway 395 in the west. In California, desert bighorn monitoring has been conducted since early in the second half of the twentieth century, but starting in 2013 CDFW entered an era of renewed emphasis on data collection due to the outbreak of respiratory disease, first documented at Old Dad Peak. That disease epizootic was, and continues to be, the largest documented disease outbreak in California’s Nelson bighorn sheep populations. This report summarizes monitoring efforts and management actions from November 1, 2013 through October 31, 2016; it also includes survey work conducted from May 2015 through the end of October 2016. May 2015 marked the hiring of field personnel dedicated to desert bighorn in the Bishop Field Office. During 2013-2016, CDFW conducted eight ground surveys, flew the first helicopter surveys in five years, captured and collared over 170 bighorn across thirteen mountain ranges, recovered 25 mortalities, and helped repair and bring water into bighorn drinker systems, as needed.

Resource selection of mule deer in a shrub-steppe ecosystem: influence of woodland distribution and animal behavior

Wed, 13 Nov 2019 15:05:35 -0800

Resource selection of mule deer in a shrub-steppe ecosystem: influence of woodland distribution and animal behavior - Ungulates inhabiting arid ecosystems are reliant on productive forb and shrub communities during summer months to meet nutritional demands for survival and reproduction. In the western United States, expansion of woodland vegetation into shrub-dominated communities and the potential loss of habitat are of concern with regard to animal populations reliant on robust sagebrush shrub and forb vegetation. We used mixed-effects logistic regression to model resource selection of female mule deer (Odocoileus hemionus) during the summers of 2005–2008. We considered selection at two spatial scales, and during three daily activity periods (night, crepuscular, and mid-day) corresponding to resting and foraging. We evaluated habitat variables related to vegetation type, site productivity, terrain attributes, and fine-scale abundance of pinyon–juniper cover. Those attributes allowed us to account for variation in site productivity and animal behaviors that could obscure the true relationship between density of pinyon– juniper woodland and habitat use by mule deer. We detected observable differences in habitat use by mule deer among the three activity periods with significant differences in movement rates. Deer were most active during crepuscular periods corresponding with foraging activity, and least active mid-day when temperatures were highest. Summer habitat consisted of sites with high potential productivity, greater shrub abundance, and greater proximity to riparian areas. Deer avoided high levels of tree cover (>40% coverage) at all spatial and temporal scales, and in general selection declined with increasing pinyon–juniper cover, particularly during foraging periods. Nonetheless, mule deer selected areas with low to intermediate tree cover (10% to 40%) during resting periods and avoided areas of productive shrub and forb vegetation and riparian areas, when surrounded by denser stands of pinyon–juniper cover. These results emphasize the importance of productive shrub and forb vegetation to mule deer inhabiting semi-arid regions and suggest that low levels of tree cover are beneficial, especially during resting periods. Nevertheless, dense pinyon–juniper cover was generally avoided even in areas of high site productivity. These relationships lend support to the concern that increases in large, dense stands of pinyon–juniper reduce availability of summer habitat and alter patterns of resource selection for mule deer, a shrub-dependent ungulate.

Eastern Sierra Nevada Low Elevation Mesocarnivore Annual Report 2017

Fri, 21 Jun 2019 11:07:56 -0700

Eastern Sierra Nevada Mesocarnivore Annual Report - The Inland Desert Region Wildlife Program conducts resource assessment activities necessary to monitor the health and condition of wildlife populations, assess the anthropogenic and environmental impacts to wildlife resources, and to manage wildlife populations. Climate change, disease outbreaks, extreme weather events, and California Department of Fish and Wildlife (Department) policy and regulation changes are a few factors that can affect wildlife populations so it is within our trustee and responsible roles as an agency to monitor wildlife populations. In the fall of 2014, the Eastern Sierra Nevada Bobcat Study (ESNBS) was initiated in response to the proposed statewide ban on bobcat (Lynx rufus) trapping in spring of 2014. The main objective of this study was initially to standardize survey techniques for bobcats that would allow the Department to better monitor and manage low elevation (<9,000 ft) bobcat populations in Inyo and Mono Counties. The ESNBS has conducted population surveys and deployed GPS collars on bobcats to learn more about Eastern Sierra bobcat densities and population characteristics. After three years of focusing mainly on the bobcat population, the focus has shifted to include all lowerelevation mesocarnivore species. We have changed the name of the study to the Eastern Sierra Nevada Low Elevation Mesocarnivore Study to reflect the change in our objectives.

Population Ecology and Summer Habitat Selection of Mule Deer in the White Mountains: Implications of Changing Landscapes and Variable Climate

Wed, 15 May 2019 11:08:27 -0700

Population Ecology and Summer Habitat Selection of Mule Deer in the White Mountains - Changes in landscape composition have the potential to negatively influence animal populations through shifts in dominant plant communities, loss of important forage items, or changes in structural components of habitat. In the western United States, expansion of woodland vegetation into shrub dominated communities is of concern, particularly with regard to animal populations reliant on robust sagebrush and shrub vegetation. Once established, trees can out-compete shrubs and herbaceous plants resulting in declines in abundance and diversity of shrub-forb vegetation, which female mule deer are reliant on during summer months to meet nutritional demands and to provide hiding cover for young. As a result, shifts in the distribution of pinyon-juniper woodland and increases in tree densities could negatively affect mule deer population. The study had two primary objectives, (1) to determine summer habitat composition of female mule deer in the White Mountains of California and eastern Nevada, and assess implications of pinyon-juniper expansion on habitat availability, and (2) evaluate the status of the population relative to nutritional carrying capacity and determined the influence of habitat and precipitation on demographic rates.

Peninsular Bighorn Sheep Recovery 2015 Annual Report

Wed, 24 Aug 2016 09:48:47 -0700

2015 Annual report peninsular bighorn sheep - Desert bighorn sheep (Ovis canadensis nelsoni) inhabit the desert slopes of the Peninsular Ranges of southern California and extend into the mountains of Baja California in Mexico. The population within the Peninsular Ranges was first listed as threatened in 1971 under the California Endangered Species Act. In 1974, the population was estimated at 1,171 (Weaver 1975) but by 1996 the rangewide population estimate had declined to only 276 adult sheep (USFWS 2000). Peninsular bighorn sheep were listed as a federally endangered population segment in 1998 (63 FR 13134) due to: 1) habitat fragmentation, degradation, and loss by urban and commercial development; 2) disease; 3) predation coinciding with low population numbers; 4) response to human disturbance; 5) insufficient lamb recruitment; 6) nonnative toxic plants; and 7) prolonged drought (USFWS 2000). Presently, the population of desert bighorn sheep in the Peninsular Ranges is considered to be stable to increasing based on the most recent 2010 California Department of Fish and Wildlife (CDFW) rangewide survey estimate of 955 bighorn sheep.

Estimated Distribution of Deer Habitat in California's General Deer Hunt Zones

Fri, 06 Nov 2015 11:15:36 -0800

Estimated Distribution of Deer Habitat in California's General Deer Hunt Zones - Estimated Distribution of Deer Habitat in California's General Deer Hunt Zones 2008 California Wildlife Distribution Maps

Habitat Selection by Mountain Sheep in the Sonoran Desert: Implications for Conservation in the United States and Mexico

Thu, 22 Jan 2015 09:50:53 -0800

Habitat Selection by Mountain Sheep in the Sonoran Desert: Implications for Conservation in the United States and Mexico - We used aerial telemetry to determine diurnal habitat use by mountain sheep (Ovis canadensis) in the East Chocolate Mountains, Imperial County, California during June 1992 through December 1993. We empirically derived a 95% circular error polygon (3.14 km2 around each telemetry point) and this was fundamental for habitat analyses for which we used vector and raster based Geographic Information System processing. Eight habitat variables (elevation, slope, aspect, terrain roughness, vegetation, and distances to water, escape terrain and human disturbance) were evaluated by gender for hot and cool seasons of the year.

Impacts Of Cattle Grazing On Bighorn Sheep III

Fri, 12 Dec 2014 14:14:22 -0800

Impacts Of Cattle Grazing On Bighorn Sheep - One of a series of reports attempting to document the potential effects of domestic cattle grazing on bighorn sheep.

Impacts Of Cattle Grazing On Bighorn Sheep II

Thu, 11 Dec 2014 14:24:51 -0800

Impacts Of Cattle Grazing On Bighorn Sheep - One of a series of reports attempting to document the potential effects of domestic cattle grazing on bighorn sheep.

Impacts Of Cattle Grazing On Bighorn Sheep I

Thu, 11 Dec 2014 14:22:42 -0800

Impacts Of Cattle Grazing On Bighorn Sheep I - One of a series of reports documenting potential effects of domestic cattle grazing on bighorn sheep.

Rainfall, El Nino, and dynamics of mule deer in the Sonoran Desert, California

Mon, 09 Apr 2012 14:14:50 -0700

Rainfall, El Nino, and dynamics of mule deer in the Sonoran Desert, California - We used long-term El Nifio southern oscillation (ENSO), rainfall, and deer harvest records to investigate effects of ENSO and rainfall on mule deer (Odocoileus hemionus) population trends in the Sonoran Desert, south- eastern California, USA. We found significant relationships between the southern oscillation index and rainfall (R2 = 0.38, P < 0.001), and between rainfall and annual deer harvest (R2 = 0.25, P < 0.001). We also found that deer harvest (i.e., an index of deer abundance) in any year was related to accumulations of rainfall >5 years before that hunting season (R2 = 0.34), whereas the change in harvest between years (i.e., an index of rate of population change) was most related to rainfall the year immediately prior to that hunting season (R2 = 0.15). Fluctuations in deer populations in the deserts of California ultimately may be caused by ENSO events

Overlap in diet and habitat between the mule deer (Odocoileus hemionus) and feral ass (Equus asinus) in the Sonoran Desert

Mon, 09 Apr 2012 14:08:25 -0700

Overlap in diet and habitat between the mule deer (Odocoileus hemionus) and feral ass (Equus asinus) In the Sonoran Desert - We studied use of habitats and diets of mule deer (Odocoileus hemionus) and feral asses (Equus asinus) by comparing vegetation (i.e., normalized-difference-vegetation index, normalized-differencevegetation- index rate), elevation, slope, and distances to water-catchments, roads, rivers and canals, and washes used by each species. Distribution was similar with respect to distances to roads, catchments, and rivers and canals in winter, normalized-difference-vegetation index and distance to catchments in spring, distance to rivers and canals in summer, and slope in autumn. Diets (from microhistological analysis of feces) revealed biologically significant overlap during the abundant-forage season (simplified Morisita index >0.60). Diets of mule deer had high proportions of browse (76–85%) in all seasons and low proportions of grasses (1–2%) and forbs (4–8%); whereas, diets of feral asses contained less browse (65–72%) and more grasses (12–16%) and forbs (13–20%).

Body condition of mule deer in the Sonoran Desert is related to rainfall

Mon, 09 Apr 2012 13:46:28 -0700

Body condition of mule deer in the Sonoran Desert is related to rainfall - We investigated associations between rainfall and body condition of desert mule deer (Odocoileus hemionus eremicus) in the Sonoran Desert, California, using two indices of condition based on body fat: a categorical score based on subcutaneous fat and visibility of bones under the skin of free-ranging animals via remote photography, and percent fat in the marrow of long-bones of harvested males. There were positive correlations between rainfall and proportion of deer in good condition (r 5 0.60, P 5 0.064) and proportion of deer in fair condition (r 5 0.70, P 5 0.017). Proportion of deer in poor condition was negatively correlated with rainfall (r 5 20.72, P 5 0.020). There was evidence of a year effect on percent fat in the marrow of metacarpus and metatarsus bones (P 5 0.030), such that years in which deer had lower average marrow fat coincided with years having lower rainfall. These findings demonstrate the importance of rainfall, likely operating through quantity or quality of forage, on body condition of mule deer, which have subsequent effects on demography. An understanding of these patterns will continue to be important for the conservation of ungulate populations in arid regions.

Gradients of forage biomass and ungulate use near wildlife water developments

Mon, 09 Apr 2012 13:42:40 -0700

Gradients of forage biomass and ungulate use near wildlife water developments - The addition of wildlife water developments (i.e., catchments) to arid areas may concentrate foraging by desert ungulates and decrease forage availability near catchments. We looked for gradients in forage biomass and use by mule deer (Odocoileus hemionus) and bighom sheep (Ovis canadensis) along dry riparian streams near catchments. We measured forage biomass and pellet group density in transects following vegetation along edges of desert washes near catchments and in control washes with catchments >3 km away. Ungulate use, as reflected by pellet group density, was greatest in washes with catchments in place >3 years. There was some evidence for a gradient in pellet density in spring (slope = -0.012, P = 0.088) and summer (slope = -0.013, P = 0.015), and for differences between catchment and control transects in all seasons (13-46 pellet groups/ha, P < 0.077). We found no evidence of an effect of catchments on forage biomass in nearby washes: we detected no gradient in forage biomass nor an overall difference between washes with catchments and those without (P > 0.15). Desert ungulates used washes near catchments in our study area but had minimal effects on nearby vegetation.

Factors affecting habitat use and distribution of desert mule deer in an arid environment

Mon, 09 Apr 2012 13:39:01 -0700

Factors affecting habitat use and distribution of desert mule deer in an arid environment - We studied habitat use by desert mule deer (Odocoileus hemionus eremicus) in the Sonoran Desert to understand the relative importance of vegetation, terrain characteristics, human disturbances, and water sources in determining their distribution. We located 44 radiocollared female mule deer weekly over 5 years. In spring, when water was most scarce, deer were in areas with lower elevations, shallower slopes, and greater normalized difference vegetation index (NDVI) rates, when compared to random locations. Use of water developments (i.e., catchments) during spring was evident but their effect on deer distribution was small relative to other factors, and their importance varied by animal. More deer locations were recorded in areas of higher NDVI rate in spring, summer, and autumn, but they were also further from washes in autumn. The deer we monitored used lower elevations in spring and higher elevations during the rest of the year. The effect of slope was strong in all seasons. However, deer tended to select shallow slopes in spring and steep slopes during the rest of the year. Deer avoided roads in summer and autumn but were closer to them in winter. They avoided rivers or canals in summer but were closer to those features in autumn. Our results suggest that terrain characteristics in all seasons (slope and elevation), as well as forage quality in 3 of 4 seasons (as indexed by NDVI rate) were most important in determining distribution of deer. Concomitantly water catchments had a measurable, but minor, role during hot, dry conditions. We recommend investigators continue to evaluate the importance of water developments relative to other habitat factors, particularly via the use of multivariate studies, global positioning system technology, adaptive management, and temporary closure of water developments known to be used by radiocollared deer.

Demography of desert mule deer in southeastern California

Mon, 09 Apr 2012 13:34:25 -0700

Demography of desert mule deer in southeastern California - Desert mule deer, Odocoileus hemionus eremicus, occur at low densities in the Sonoran Desert of southeastern California and consequently are difficult to monitor using standard wildlife techniques. We used radiocollared deer, remote photography at wildlife water developments (i.e., catchments), and mark-recapture techniques to estimate population abundance and sex and age ratios. Abundance estimates for 1999-2004 ranged from 40 to 106 deer, resulting in density estimates of 0.05-0.13 deer/km2. Ranges in herd composition were 41-74% (females), 6-31% (males), and 6-34% (young). There was a positive correlation (R = 0.73, P = 0.051) between abundance estimates and number of deer photographed / catchment-day, and that relationship may be useful as an index of abundance in the absence of marked deer for mark-recapture methods. Because of the variable nature of desert wildlife populations, implementing strategies that recognize that variability and conserving the habitat that allow populations to fluctuate naturally will be necessary for long-term conservation.

Seasonal forage use by desert mule deer in southeastern California

Mon, 09 Apr 2012 13:29:30 -0700

Seasonal forage use by desert mule deer in southeastern California - We used microhistological analysis of fecal pellets to identify plant species in diets of desert mule deer (Odocoileus hemionus eremicus) in southeastern California and to investigate seasonal changes in use of forage classes. We identified 34 taxa of plants, 7 of which have not been reported previously in the diets of desert mule deer. Browse species were abundant in diets during all seasons, but were lowest in spring, when forb species were most commonly observed. Use of succulents generally was low, with highest use occurring in autumn (3 to 24%). Grasses composed #1% of the diet in all seasons. Our findings emphasize the diversity of plant species used by desert mule deer and, consequently, the importance of conserving habitats that provide for that diversity.

Desert Deer Investigation Launched

Tue, 03 Apr 2012 12:42:59 -0700

Desert Deer Investigation Launched - Radio telemetry study of habitat use patterns of Sonoran desert mule deer.

A Comparison of Mule Deer Survey Techniques in the Sonoran Desert

Tue, 03 Apr 2012 12:39:26 -0700

A Comparison of Mule Deer Survey Techniques in the Sonoran Desert - Helicopter surveys, ground surveys and interviews with hunters were compared as methods to obtain mule deer demographic data in the Sonoran desert.

Burro Deer Herd Management Plan

Tue, 03 Apr 2012 12:33:37 -0700

Management Plan for Burro Deer Herd - Management Plan for Burro Deer Herd

Population dyanmics of Peninsular bighorn sheep in the Santa Rosa Mountains, California, 1983-1994

Tue, 27 Mar 2012 11:15:32 -0700

Population dyanmics of Peninsular bighorn sheep in the Santa Rosa Mountains, California, 1983-1994 - Fall (1983-1994) helicopter surveys of Peninsular bighorn sheep (Ovis canadensis cremnobates) in the Santa Rosa Mountains (SRM) of Southern California were used to determine annual population estimates and dynamics. Age structure and sex ratio data, as well as maintenance recruitment ratios for population stability, were also examined. During these 12 years, ram:ewe:lamb:yearling ratios averaged 44.9: 100:25.2: 17.4. Long-term suppressed recruitment following a disease epizootic in the late 1970s caused a 69.1 percent population decline from 374.0 + 10 adult bighorn in 1984 to 115.5 + 24 in 1994. Spatial analysis showed that the decline occurred throughout the SRM. The bighorn population decreased at an average annual rate of 17.8 percent from 1984 to 1990, then stabilized at a density of only 0.15 bighorn / km2.

Flawed model has serious conservation implications: Response to Turner et al.

Tue, 27 Mar 2012 11:07:59 -0700

Flawed model has serious conservation implications - Turner et al. (2004) developed a habitat selection model for a population of desert bighorn sheep (Ovis canadensis) in the Peninsular Ranges of southern California that is listed as a threatened and endangered population by the state of California and the federal government, respectively. We are concerned that the recent publication of an article by Turner et al. (2004) could be detrimental to the management and recovery of bighorn sheep in the Peninsular Ranges because it lends credibility to a flawed analysis of bighorn sheep habitat-use patterns. The model attempts to extrapolate conclusions from a limited subset of bighorn sheep data that is not representative of the study area and was not gathered in a manner conducive to the analysis methods used by the authors. The authors classified habitat pixels as "active" or "inactive" based on the presence-absence of bighorn sheep observations without considering monitoring intensity. Turner et al. (2004) also failed to consider the implications of basing their model almost entirely on a bighorn sheep subpopulation known to have atypical habitat selection patterns. This subpopulation in the northwestern Santa Rosa Mountains frequently used food and water sources within hillside urban areas. Because the Turner et al. (2004) model was developed using data primarily from this atypical subpopulation, the model has low external validity and is unlikely to accurately predict habitat selection by other bighorn sheep subpopulations in the Peninsular Ranges. Furthermore, with the NW sub- population used in model development now excluded from urban areas, the Turner et al. (2004) model is unlikely to accurately predict habitat selection patterns of even this subpopulation. We suggest the Turner et al. (2004) model is at best only applicable to this subpopulation between the years 1994-1998.

Peninsular bighorn sheep recovery plan - 5 year review

Mon, 12 Mar 2012 16:38:38 -0700

Peninsular bighorn sheep recovery plan - 5 year review - The U.S. Fish and Wildlife Service (Service) is required by section 4(c)(2) of the Endangered Species Act (Act) to conduct a status review of each listed species at least once every 5 years. The purpose of a 5-year review is to evaluate whether or not the species’ status has changed since it was listed. Based on the 5-year review, we recommend whether the species should be removed from the list of endangered and threatened species, be changed in status from endangered to threatened, or be changed in status from threatened to endangered. Our original listing of a species as endangered or threatened is based on the existence of threats attributable to one or more of the five threat factors described in section 4(a)(1) of the Act, and we must consider these same five factors in any subsequent consideration of reclassification or delisting of a species. In the 5-year review, we consider the best available scientific and commercial data on the species, and focus on new information available since the species was listed or last reviewed. If we recommend a change in listing status based on the results of the 5-year review,we must propose to do so through a separate rule-making process defined in the Act that includes public review and comment.

Distribution and abundance of bighorn sheep in the Peninsular Ranges, California

Mon, 12 Mar 2012 14:12:38 -0700

The current population structure and past trends in abundance of endangered bighorn sheep (Ovis canadensis) in the Peninsular Ranges of California - We examined the current population structure and past trends in abundance of endangered bighorn sheep (Ovis canadensis) in the Peninsular Ranges of California using a variety of approaches. Direct observations of radiocollared animals (N= 90 ewes and 24 rams) during 35 months suggested that bighorn distribution in the Peninsular Ranges was fragmented into 28 groups of ewes. These findings were supported by aerial-telemetry locations of radiocollared ewes obtained during 43 fixed-wing flights and observations of uncollared bighorn sheep made during 2 helicopter surveys. Boundaries between ewe groups coincided, in 4 cases, with paved roads, leading us to speculate that some fragmentation was recent and artificial. Abundance estimates derived for 5 of the 8 ewe groups in 1994 and 1996 revealed a recent decline of 28% in this portion of the range. Adult population estimates were generated and combined with existing estimates for the remainder of the range to produce es- timates of 347 and 276 bighorn sheep in the Peninsular Ranges north of the United States-Mexico border in 1994 and 1996, respectively. Linear regression analysis of 26 years of waterhole count data, collected at 30 sites representing regions used by 4 ewe groups, indicated that numbers of ewes had declined in 2 of these regions since 1971, but that 2 regions had been inhabited by stable ewe populations during this period. We suggest that groups of bighorn sheep in different portions of the Peninsular Ranges are under local influences and exhibit independent population dynamics.

Bighorn sheep habitat use and selection near an urban environment

Mon, 12 Mar 2012 14:11:17 -0700

Bighorn sheep habitat use and selection near an urban environment - To further understand the impact of urban development on wildlife populations, we examined habitat use and selection by female bighorn sheep Ovis canadensis in two endangered subpopulations near a metropolitan area in southern California. One subpopulation, which had previously been found to have low reproductive success, selected urban environments while the other did not use urban areas. In the subpopulation that used urban areas, females had smaller core activity areas and selected lower elevations and gentler slopes. These females used urban sources of water but a clear relationship between levels of urban use and periods of increased water need was not evident. Diet quality was higher among females that selected urban areas, and this increase was correlated with the level of urban use. Thus, optimal foraging behavior may have contributed to the selection of urban areas. Urban use was lowest during peak months of parturition, suggesting that reproductive strategies may also have influenced temporal patterns of urban use. Although urban areas provided bighorn sheep with forage and water resources, the use of these areas may have substantial costs. For example, females using urban areas had internal parasites that were not found elsewhere in the Peninsular Ranges.

Fecal DNA analysis and risk assessment of mountain lion predation of bighorn sheep

Mon, 12 Mar 2012 14:06:45 -0700

Fecal DNA analysis and risk assessment of mountain lion predation of bighorn sheep - We analyzed fecal DNA to identify individual mountain lions (Puma concolor) associated with kills of federally listed endangered bighorn sheep (Ovis canadensis) in the Peninsular Ranges of California from 1993-1999. We identified 18 different mountain lions at 26 bighorn sheep kill sites, as well as 5 mountain lions not associated with bighorn sheep mortalities. Thirteen genotypes were each identified at only 1 kill site, while 2 genotypes were unambiguously detected at multiple kill sites. We developed a Monte Carlo simulation model incorporating the DNA data to evaluate the benefits (bighorn sheep saved and reduction in extinction risk) and costs (mountain lions removed) of mountain lion removal under 2 management strategies for a 5-year period. One strategy removed individual mountain lions only after they killed 1 bighorn sheep (kill-site removal), while the other strategy removed mountain lions found anywhere in bighorn sheep habitat (habitat removal). The habitat removal strategy was equal or superior to the kill-site removal in terms of reducing extinction risk for all sizes of ewe populations. However, the kill-site strategy more efficiently targeted bighorn sheep predators and resulted in the removal of fewer non-bighorn sheep-killing mountain lions than the less selective habitat removal strategy. Removal of 1-2 mountain lions per year by either strategy effectively decreased extinction risk for populations consisting of 15-30 ewes, while more intensive removal (3-4 mountain lions per year) was necessary to reduce the risk for smaller populations containing <15 ewes. Removal of mountain lions for a short period of time may be the best option available for bighorn sheep populations in immediate danger of extinction due to mountain lion predation. Given that site-specific information and several assumptions were incorporated in our model, we strongly recommend that individualized and updated assessments be performed on the potential costs and benefits of predator control actions so that the rescue of 1 species or population does not jeopardize another.

2008 Annual report peninsular bighorn sheep

Mon, 12 Mar 2012 12:35:16 -0700

2008 Annual report peninsular bighorn sheep - This report highlights information collected by the California Department of Fish Game (CDFG) over the reporting period, 1 January 2008 through 31 December 2008 relating to bighorn sheep (Ovis canadensis) in the Peninsular mountain ranges of southern California. The Peninsular bighorn sheep population contains nine designated recovery regions occupying portions of western Riverside and Imperial Counties and eastern San Diego County. CDFG conducted monitoring activities in seven of nine recovery regions located east of Highway 74: Central Santa Rosa Mountain (CSRM), Southern Santa Rosa Mountain (SSRM), Coyote Canyon (CoC), North San Ysidro Mountain (NSYM), South San Ysidro Mountain (SSYM), Vallecito Mountain (VM), Carrizo Canyon (CC). CDFG jointly monitored CSRM with the Bighorn Institute while the Northern Santa Rosa Mountain (NSRM) and San Jacinto Mountain (SJM) recovery regions located west of Highway 74 were monitored solely by BI.

Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Peninsular Bighorn Sheep and Determination of a Distinct Population Segment of Desert Bighorn Sheep (Ovis canadensis nelsoni)

Mon, 12 Mar 2012 12:19:30 -0700

Designation of Critical Habitat for Peninsular Bighorn Sheep and Determination of a Distinct Population Segment of Desert Bighorn Sheep - Designation of Critical Habitat for Peninsular Bighorn Sheep and Determination of a Distinct Population Segment of Desert Bighorn Sheep (Ovis canadensis nelsoni)

Puma predation on radiocollared and uncollared bighorn sheep

Mon, 12 Mar 2012 12:15:34 -0700

Puma predation on radiocollared and uncollared bighorn sheep - nter, University of California, Davis, CA, USA, 2Conservation Biology Institute, Borrego Springs, CA, USA and 3California Department of Fish and Game, San Diego, CA, USA Email: Sean M Clemenza - smclemenza@ucdavis.edu; Esther S Rubin - esrubin@consbio.org; Christine K Johnson - ckjohnson@ucdavis.edu; Randall A Botta - rbotta@dfg.ca.gov; Walter M Boyce* - wmboyce@ucdavis.edu Background: We used Global Positioning System (GPS) data from radiocollared pumas (Puma concolor) to identify kill sites of pumas preying upon an endangered population of bighorn sheep (Ovis canadensis) in southern California. Our aims were to test whether or not pumas selected radiocollared versus uncollared bighorn sheep, and to identify patterns of movement before, during, and after kills. Three pumas killed 23 bighorn sheep over the course of the study, but they did not preferentially prey on marked (radiocollared) versus unmarked bighorn sheep. Predation occurred primarily during crepuscular and nighttime hours, and 22 kill sites were identified by the occurrence of 2 or more consecutive puma GPS locations (a cluster) within 200 m of each other at 1900, 0000,and 0600 h. We tested the "conspicuous individual hypothesis" and found that there was no difference in puma predation upon radiocollared and uncollared bighorn sheep. Pumas tended to move long distances before and after kills, but their movement patterns immediately post-kill were much more restricted. Researchers can exploit this behavior to identify puma kill sites and investigate prey selection by designing studies that detect puma locations that are spatially clustered between dusk and dawn.

Status of bighorn sheep in California

Mon, 12 Mar 2012 11:58:34 -0700

Status of bighorn sheep in California - Status of peninsular bighorn sheep 1998-2004

Determination of critical habitat for the endangered Nelson's bighorn sheep in southern California

Mon, 12 Mar 2012 11:54:44 -0700

Determination of critical habitat for the endangered Nelson's bighorn sheep in southern California - The United States Fish and Wildlife Service’s (USFWS) designation of critical habitat for the endangered Nelson’s bighorn sheep (Ovis canadensis nelsoni) in the Peninsular Ranges of southern California has been controversial because of an absence of a quantitative, repeatable scientific approach to the designation of critical habitat. We used 12,411 locations of Nelson’s bighorn sheep collected from 1984–1998 to evaluate habitat use within 398 km2 of the USFWS-designated critical habitat in the northern Santa Rosa Mountains, Riverside County, California. We developed a multiple logistic regression model to evaluate and predict the probability of bighorn use versus non-use of native landscapes. Habitat predictor variables included elevation, slope, ruggedness, slope aspect, proximity to water, and distance from minimum expanses of escape habitat. We used Earth Resources Data Analysis System Geographic Information System (ERDAS-GIS) software to view, retrieve, and format predictor values for input to the Statistical Analysis Systems (SAS)software. To adequately account for habitat landscape diversity, we carried out an unsupervised classification at the outset of data inquiry using a maximum-likelihood clustering scheme implemented in ERDAS. We used the strata resulting from the unsupervised classification in a stratified random sampling scheme to minimize data loads required for model development. Based on 5 predictor variables, the habitat model correctly classified >96% of observed bighorn sheep locations. Proximity to perennial water was the best predictor variable. Ninety-seven percent of the observations were within 3 km of perennial water. Exercising the model over the northern Santa Rosa Mountain study area provided probabilities of bighorn use at a 30 × 30-m2 pixel level. Within the 398 km2 of USFWS designated critical habitat, only 34% had a graded probability of bighorn use to non-use ranging from >1:1 to 6,044:1. The remaining 66% of the study area had odds of having bighorn use <1:1 or it was more likely not to be used by bighorn sheep. The USFWS designation of critical habitat included areas (45 km2) of importance (2.5 to >40 observations per km2 per year) to Nelson’s bighorn sheep and large landscapes (353 km2) that do not appear to be used (<1 observation per km2 per year).

Modelling demographic processes in an endangered population of bighorn sheep

Mon, 12 Mar 2012 11:45:48 -0700

Modelling demographic processes in an endangered population of bighorn sheep - We developed a demographic simulation model to explore how population vital rates, initial size, and the addition of animals influenced the viability of an endangered population of bighorn sheep (Ovis canadensis) consisting of 8 subpopulations. Perturbation analyses indicated that quasi-extinction risk was more sensitive to changes in adult female survival than to changes in reproduction or survival of young animals. This pattern was similar in 8 subpopulations that had different initial sizes, survival rates, and recruitment rates. Subpopulation viability was related to the initial number of females and to adult female survival, but not reproduction. Management actions that increase adult survival may be most effective when implemented in the largest subpopulations, whereas actions involving the addition of animals may be most effective if implemented in subpopulations with high survival rates. Subpopulation augmentation in yearly increments was more effective at reducing quasi-extinction risk than was adding the same total number of animals at the beginning of the simulation. The level of augmentation needed to substantially reduce quasi-extinction risk exceeded reported levels of female movement among populations or subpopulations. This finding led us to speculate that rescue effects, which are uncommon events for bighorn sheep, may be too rare or of inadequate magnitude under current conditions to effectively reverse bighorn sheep population declines.

Assessment of predictive habitat models for bighorn sheep in California's Peninsular Ranges

Mon, 12 Mar 2012 11:42:05 -0700

Predictive habitat models for a bighorn sheep (Ovis canadensis) population in the Peninsular Ranges of southern California - We developed predictive habitat models for a bighorn sheep (Ovis canadensis) population in the Peninsular Ranges of southern California, USA, using 2 Geographic Information System modeling techniques, Ecological Niche Factor Analysis (ENFA) and Genetic Algorithm for Rule-set Production (GARP). We used > 16,000 Global Positioning System locations from 34 animals in 5 subpopulations to develop and test ENFA and GARP models, and we then compared these models to each other and to the expert-based model presented in the United States Fish and Wildlife Service's Recovery Plan for this population. Based on a suite of evaluation methods, we found both ENFA and GARP to provide useful predictions of habitat; however, models developed with GARP appeared to have higher predictive power. Habitat delineations resulting from GARP models were similar to the expert-based model, affirming that the expert-based model provided a useful delineation of bighorn sheep habitat in the Peninsular Ranges. In addition, all 3 models identified continuous bighorn sheep habitat from the northern to southern extent of our study area, indicating that the Recovery Plan's recommendation of maintaining habitat connectivity throughout the range is an appropriate goal.

Captive breeding and reintroduction evaluation criteria: a case study of peninsular bighorn sheep

Mon, 12 Mar 2012 11:37:25 -0700

Evaluation of captive breeding program desert bighorn sheep. - Captive breeding and reintroduction programs are rarely evaluated, and assessment criteria vary widely. We used the following criteria to evaluate a bighorn sheep (Ovis canadensis) augmentation program: (1) survival and recruitment rates in the captive population, (2) survival of released animals, (3) recruitment of released animals, (4) growth rate of the reintroduced or augmented population, and (5) establishment of a viable wild population. Captive bighorn survival and recruitment was high, averaging 0.98 (SD = 0.05) and 71.0% (SD = 19.4), respectively. Annual survival of free-ranging captive-reared bighorn (n = 73, x = 0.80, SD = 0.11) did not differ (Z = -0.85, p = 0.40; n = 14) from survival of wild-reared bighorn (n = 43, x = 0.81, SD = 0.12). Recruitment was unusually low for both captive-reared (x = 13.7%, SD = 0.24) and wild-reared ewes (x = 13. 7%, SD = 0.20). Although reintroduction did not result in population growth or establishment of a viable population, it helped prevent extirpation of the reinforced deme, preserved metapopulation linkage, and aided habitat preservation. Chronic low recruitment and low adult survivorship precluded achievement of criteria 3-5. Environmental conditions in the release area also appeared to hinder program success. Standard evaluation criteria for ongoing reintroductions allow for informative assessments and facilitate comparisons needed to refine reintroduction science as a recovery tool for threatened or endangered populations.

Genetic variation and population structure in desert bighorn sheep: implications for conservation

Mon, 12 Mar 2012 11:30:36 -0700

Genetic variation and population structure in desert bighorn sheep - Bighorn sheep populations experienced a drastic reduction in both distribution and abundance until the advent of modern wildlife management, where improving viability of extant populations and translocating animals into historical habitat range have been the most important management policies. The fact that subspecies relationships among bighorn are ambiguous, together with the importance of selecting appropriate source stock and the expense of translocation projects, makes an understanding of subspecies relationships and genetic variation, within and between populations, important for the management and conservation of this species. In this study, genetic variation in 279 bighorn sheep from 13 study sites in Arizona, California, New Mexico and Alberta, Canada were examined by analyzing ten microsatellite loci to determine interpopulation differentiation and relationships between closely related taxa. All populations contained a substantial amount of genetic variation. Genetic differences between populations were large and roughly proportional to geographic distance. The significance of this to desert subspecies relationships and management is discussed.

Recovery plan for bighorn sheep in the Peninsular Ranges, California

Mon, 12 Mar 2012 11:26:48 -0700

Recovery Plan for bighorn sheep in Peninsular Ranges, California - Recovery Plan for endangered bighorn sheep in Peninsular Ranges, California.

Mountain lion predation of bighorn sheep in the peninsular ranges, California

Mon, 12 Mar 2012 11:19:33 -0700

Survival and cause-specific mortality of 113 radiocollared bighorn sheep (Ovis canadensis) in the Peninsular Ranges of southern California from November 1992 - May 1998. - Survival and cause-specific mortality of 113 radiocollared bighorn sheep (Ovis canadensis) in the Peninsular Ranges of southern California from November 1992 - May 1998. Mountain lion predation was the most frequent cause of mortality and was the cause of death for 69% (42/61) of all mortalities. Predation was documented during all months of the year except June and 62% (26/42) of predation events occurred from December through March. We propose that a sustained high level of predation by mountain lions may impede the recovery of this population.

Reproductive strategies of desert bighorn sheep

Mon, 12 Mar 2012 11:12:38 -0700

Temporal breeding patterns of bighorn sheep (Ovis canadensis) in the Pen- insular Ranges of California to determine the degree of seasonality and identify potential selection for seasonal breeding. - We examined temporal breeding patterns of bighorn sheep (Ovis canadensis) in the Pen- insular Ranges of California to determine the degree of seasonality and identify potential selection for seasonal breeding in this low-latitude desert environment. During a 4-year period, births occurred during 7 months of the year, but 87% of young were born in February-April and 55% were born in March. Peak months of mating and parturition remained relatively constant across years and among different regions of the Peninsular Ranges, and young born in February through April had greater survival than those born later. Female age influenced lamb survival but not timing of parturition. Successful recruitment of young by an adult female had a weak but significant negative effect on the survival of that female's offspring the following year. Previous reproductive history of a female did not influence offspring production or timing of parturition. Months of peak parturition followed annual winter rains and, therefore, were likely to coincide with periods of high plant productivity. Furthermore, most young were born before the hot, arid summer months. We concluded that bighorn sheep in the Peninsular Ranges are seasonal breeders and that climate patterns likely act as ultimate factors in shaping the breeding season.

The ecology of peninsular bighorn sheep in the San Jacinto Mountains, California

Mon, 12 Mar 2012 11:01:51 -0700

Status of peninsular bighorn in the San Jacinto Mountains in 1997 - In this study, we investigated a small population of desert bighorn sheep to obtain baseline health and demographic information and to develop management recommendations aimed at regaining population viability.

A morphometric reevaluation of the peninusular bighorn subspecies

Mon, 12 Mar 2012 10:40:56 -0700

Peninsular bighorn subspecies is part of Ovis canadensis nelsonii - Cowan's (1940) taxonomy of North American wild sheep (Ovis canadensis) has been used for a half century. However, Ramey's (1993) mitochondrial DNA analysis, and his reanalysis of Cowan't original morphometric data failed to find validity in Cowan's desert subspecies divisions. Cowan's desert subspecies were instead found to be a result of small sample sizes and different age distributions among samples. This study reevaluates the Peninsular subspecies (O. c. cremnobates) and found that the Peninsular subspecies is polytpic taxon of the Nelson subspecies.