AERIAL DISTANCE SAMPLING TO ESTIMATE ABUNDANCE OF TULE ELK POPULATIONS AND A COMPARISON TO A CONCURRENT FECAL DNA SPATIAL CAPTURE-RECAPTURE SURVEY
|Tom Batter; California Department of Fish and Wildlife; Thomas.Batter@wildlife.ca.gov; Russ Landers, Kristin Denryter, Josh Bush|
Tule elk (Cervus canadensis nannodes) populations in California historically have been monitored using aerial surveys to conduct minimum counts that do not address detection biases, thus providing limited inferences. To provide statistically robust abundance estimates, we applied multiple covariate distance sampling (MCDS) during helicopter surveys for tule elk in three Elk Management Units (EMUs) in Colusa and Lake Counties, CA, in 2018 and 2019. We selected covariates to explain detection probability including vegetation cover, group size, and survey year. We also compared estimates and costs with results from a concurrent fecal DNA spatial capture-recapture (SCR) survey. We estimated a two-year average total population size of N = 674 elk (90% CI = 501–907) in our survey area, which was similar to N = 658 elk (90% CI = 577–751) from SCR estimates; overall precision was greater (CV = 0.08; range = 0.11–0.30 by population) for SCR than for MCDS (CV = 0.18; range = 0.22–0.43 by population). Total cost of SCR and MCDS surveys was $98,326 and $147,324, respectively. While SCR efforts were more precise and less expensive overall, our MCDS approach reduced staff time by 64% (587 person-hours) and the number of survey days by 87% (64 days). Our methods using MCDS could be used in other similar study areas to estimate abundance of clustered large mammals at the broad scale, particularly in cases when land access for alternative ground-based surveys is limited.
MIGRATORY STRATEGIES AND INTEGRATED STEP SELECTION ANALYSIS OF PRONGHORN (ANTILOCAPRA AMERICANA) ON THE MODOC PLATEAU
|Colton J. Wise; Oregon State University; firstname.lastname@example.org; Clinton W. Epps, Robert S. Spaan, Brian R. Hudgens, Tal Avgar|
Anthropological effects have impacted both habitat and the ability of organisms to move across landscapes freely. For pronghorn (Antilocapra americana) barriers such as fences and roads inhibit movement. Understanding migratory strategies and integrated step selection (iSSA) of pronghorn on the Modoc Plateau would improve management. We used location data from 97 GPS-collared pronghorn collected over six years to distinguish migratory strategies. We identified individual migratory movements and strategies using a mechanistic range shift analysis. We then used iSSA to determine how landscape characteristics influence these movements. We determined that 54 of 97 (56%) of pronghorn shifted ranges at least once. Range shifts lasted an average of 4.70 days, with individuals traveling an average distance of 24.09 km (range = 3.48–65.75 km). Migration strategy varied, with some individuals remaining as residents and others shifting up to five times/year. Our iSSA indicated that terrain roughness, tree canopy cover, fence density, and distance to roads influenced pronghorn movements. We were able to identify individuals with different migration strategies and identified landscape features that affected these movements. This study demonstrates how migratory behavior can vary within and amongst populations and will inform efforts to maintain landscape connectivity.
RESOURCE SELECTION OF INTRODUCED CALIFORNIA BIGHORN SHEEP
|Emily R Hagler; Pyramid Lake Paiute Tribe, University of Nevada, Reno; email@example.com; Kelley Steward|
California bighorn sheep (Ovis canadensis) are native species of the Great Basin, occupying high elevation, precipitous terrain. Selection of resources and movements of bighorn sheep are likely driven by the distribution of escape terrain, water sources, and the quality and availability of seasonal forage. Individuals translocated must find adequate resources to survive. As bighorn sheep become familiar with their new range, the resources that they select reflects their ability to acclimate. We introduced 21 individuals to the Lake Range in the northwest region of Nevada, which is an isolated landscape primarily within the Pyramid Lake Paiute Reservation. Our objective was to evaluate how female bighorn sheep seasonally select habitat as they become familiar with the habitat to which they were introduced. We captured and translocated bighorn sheep into the Lake Range in January of 2020, including 9 adult females. Each individual was fitted with a Vectronic GPS collar that collected twelve locations points per day. We evaluated seasonal selection of resources to determine how translocated bighorn alter their habitat selection in their first-year as compared to the second-year. Our results show that female bighorn sheep narrow in their selection of resources the second-year post translocation as compared to the first-year.
WINTER RESOURCE SELECTION BY MULE DEER FOLLOWING PINYON-JUNIPER REMOVAL
|Jason J Gundlach; University of Nevada, Reno; firstname.lastname@example.org; Kelley M. Stewart, Cody Schroeder, Joe Bennett|
Populations of mule deer (Odocoileus hemionus) are in decline throughout the Intermountain West for a multitude of reasons, including competition from wild and domestic herbivores, energy and urban development, and expansion of woody plants. A primary conservation concern for mule deer in the Great Basin ecosystem is expansion and infilling of Single-leaf pinyon pine (Pinus monophylla) and Utah juniper (Juniperus occidentalis), which provide minimal nutritional value to mule deer while outcompeting herbaceous vegetation in the understory. We investigated how removal of these trees affects movement patterns of mule deer, specifically on winter range. We captured 36 adult female mule deer in the Toiyabe Range of central Nevada from April 2018 through March 2019, with all individuals being fitted with GPS collars. Pinyon-juniper trees on mule deer winter range were removed by the U.S. Forest Service with an impact area of roughly 2,600 acres. Data obtained from GPS collars was modeled within a resource selection function framework utilizing mixed-effects logistic regression. Understanding which habitat covariates have the most predictive influence on movement for this population following a pinyon-juniper removal treatment will allow wildlife managers the ability to better assess areas of ecological importance for mule deer populations throughout the Intermountain West.
VARIATION IN RESOURCE RESOURCE SELECTION BY MULE DEER: EFFECTS OF REPRODUCTIVE STATUS AND INTERSPECIFIC COMPETITION
|Nathan J Jackson; University of Nevada, Reno; email@example.com; Kevin T. Shoemaker, Darren A. Clark, Michael J. Wisdom, Kelley M. Stewart|
Periodic declines in mule deer (Odocoileus hemionus) populations across much of their range in recent decades, garnered much interest from federal and state wildlife agencies. Effective management of mule deer requires an understanding of how they interact with their environment. Our objectives were to quantify resource use by adult female mule deer during late gestation, provisioning of offspring, and following the loss of offspring. We conducted our study on the Starkey Experimental Forest and Range in northeastern Oregon. We evaluated resource selection by mule deer using a Random Forest machine-learning approach. We assessed temporal variation in resource selection across three time periods: third trimester of pregnancy, 30 days post-parturition, and following the loss of offspring. Mule deer selected for further distances to roads during late stage pregnancy and after the loss of offspring. In contrast, mule deer selected for distances closer to roads during the 30 days post-parturition. We observed higher selection for distances closer to water while rearing young than the other two time periods. Our analysis also incorporated space use by elk (Cervus canadensis). Mule deer showed avoidance for areas with high probability of elk use across all time periods.
SELECTION OF RESOURCES BY PRONGHORN NEAR LARGE-SCALE DISTURBANCE
|Megan Osterhout; University of Nevada, Reno; firstname.lastname@example.org; Kelley Stewart, Cody Schroeder, Brian Wakeling|
Pronghorn (Antelocapra americana) are a native species in the Great Basin that occupy open habitats, such as sagebrush steppe and grasslands. Resource selection and movements of pronghorn are likely driven, in part, by water sources and open terrain that allows for escape from coursing predators. Large-scale mineral extraction such as open-pit mining, causes large-scale disturbance of landscapes occupied by pronghorn. The Cortez Mountains in the central region of Nevada are impacted by an active open pit mine located at the base of the mountain; an area used extensively by a resident population of pronghorn. Our objective was to evaluate how open-pit gold mining affected movement patterns and selection of resources by pronghorn. We captured 12 female pronghorn in the Cortez Range in January 2018. Each animal was fitted with a Vectronic GPS collar that collected six location points per day. We recorded 35,000 locations over two years, with an average distance from the mining boundary of 4,653 meters and 42% of the locations fell within the boundary. Pronghorn do not appear to avoid habitat near the mine, suggesting they may have adapted to living in a high-disturbance environment.