Big Game I

Contributed Oral

 
Mule Deer and Anthropogenic Change: Effects of Agricultural Encroachment on Movement, Morphology, and Population Performance
Levi Heffelfinger, David G. Hewitt, Shawn Gray, Randy W. DeYoung, Aaron Foley, Timothy Fulbright, Louis Harveson, Warren Conway

Conversion of native rangeland to row-crop farming is accelerating the process of habitat fragmentation in the Southern Great Plains. However, the effects of encroaching agriculture on wildlife are poorly understood.  We evaluated how presence of agriculture influenced resource selection and linked habitat use to life metrics of mule deer (Odocoileus hemionus) in the Panhandle region of Texas. We collected multi-year movement (via GPS collars) and morphometric measurements from 122 males and 185 females. We assessed mule deer resource selection at different spatio-temporal scales and tested functional responses of agriculture availability towards mule deer use. Cropland only accounted for 3-14% use and we observed greater selection for cropland during winter than summer months. Mule deer exhibited a quadratic functional response, where use of agriculture increased in proportion with availability, then decreased when >20% land cover was cropland. Males that used cropland in summer months relative to those that did not had greater body condition, and therefore endogenous reserves to allocate towards reproduction. Further, female cropland use during gestation increased the probability of lactating in autumn, an indicator of successfully recruiting young. The presence of crops can provide a nutritional subsidy to wildlife, but habitat selection functional responses indicate there is a threshold beyond which cropland is no longer beneficial to mule deer. Understanding the influence of anthropogenic changes on the landscape will help mitigate human-wildlife interactions and aid in adaptive management plans for mule deer in the Great Plains.

 
Responses to Natural Gas Development Differ by Season for Two Migratory Ungulates
Mallory Sandoval Lambert, Jerod Merkle, Hall Sawyer

While migrating, animals make directionally persistent movements and may only respond to human-induced rapid environmental changes (HIREC), such as climate and land-use change, once a threshold of HIREC is surpassed. In contrast, while on winter range, animals make tortuous movements while foraging and may have flexibility to adjust the location of their winter range and the intensity of use within it to minimize interactions with HIREC. HIREC poses a formidable challenge to terrestrial migrants, with climate change advancing the timing of spring phenology, and land-use change rapidly altering habitat within migration routes and seasonal ranges. We hypothesized that behavioral responses to HIREC would be linear while animals are on winter range and nonlinear while animals are migrating. We tested this hypothesis using a decade of GPS collar data from migratory mule deer (Odocoileus hemionus; n = 56 migration, 143 winter) and pronghorn (Antilocapra americana; n = 70 migration, 89 winter) that winter on and migrate through a natural gas field in western Wyoming. We used energy infrastructure (i.e., well pads and roads) as an index of HIREC and evaluated animal responses across three spatial scales during winter and migration periods. During migration, both species were reluctant to abandon traditional migratory routes until a disturbance threshold was surpassed, after which they avoided HIREC. For pronghorn, thresholds ranged from 1-9% surface disturbance, whereas mule deer thresholds were consistently ~3%. In contrast to the non-linear responses during migration, both species avoided HIREC linearly while on winter range. Our study suggests that animal responses to HIREC are mediated by season. Our results provide further evidence of ungulates avoiding human disturbance on winter range and reveal disturbance thresholds that trigger mule deer and pronghorn responses during migration – information that managers can use to maintain the ecological function of migration routes and winter ranges.

 
Behavioral Responses to Increasing Temperatures Across Individuals and Populations of Large Mammals
Rebecca R. Thomas-Kuzilik, Justine Becker, Jeffrey Beck, Aly Courtemanch, Gary Fralick, Chris Geremia, L. Embere Hall, Matthew Kauffman, Blake Lowrey, Hollie Miyasaki, Hall Sawyer, Douglas Smith, Daniel Stahler, Jerod Merkle

Behavioral plasticity is expected to play an increasingly important role in animals’ ability to mitigate heat stress. Yet, a comparative assessment of plasticity across populations and species of large mammals is lacking. Using summer GPS location data from 1068 unique animal-years representing 17 populations of 9 species of large mammals in the Rocky Mountains (USA), we implemented a resource selection function framework to: 1) quantify behavioral plasticity in response to increasing temperatures, 2) calculate the magnitude of plasticity for each population, 3) quantify variation in plasticity among individuals within each population, and 4) test hypotheses to explain differences in population plasticity and individual variation. We found that all species and populations modified their habitat selection and movement characteristics as temperatures increased, although the magnitude and specific strategy varied. Of the behavioral responses we tested (i.e., selection for elevation, aspect, tree cover, soil moisture, and movement speed), 10 of 17 populations responded most strongly to elevation, with 90% of those populations moving to higher elevations on warmer days. Pronghorn displayed the highest levels of behavioral plasticity, while the strategies of other species were more mixed. Both population plasticity and individual variation were best explained by differences in the physical environment. Population plasticity was greatest when there was higher soil moisture within a population range and when each individual had less heterogeneity in tree cover within their home range. Variation in plasticity among individuals was higher in areas with greater and more heterogeneous soil moisture, lower and more homogeneous tree cover, lower and more homogeneous elevations, and lower mean temperatures. Our work clarifies the degree to which valuable game and threatened species can display behavioral plasticity, as well as strategies they may use. Our results can also provide managers with information to more efficiently allocate resources towards habitats that facilitate behavioral plasticity.

 
State Highway 9 Wildlife Crossings and WVC Reductions: Five-Year Research Findings
Julia Kintsch, Patricia Cramer, Michelle Cowardin, Paige Singer, Bryan Roeder

In 2015 and 2016, Colorado’s first two wildlife overpasses, five underpasses, 10 miles of wildlife fencing, and other mitigation features were constructed on State Highway 9 to reduce wildlife-vehicle collisions (WVC) while maintaining permeability for wildlife. A five-year research study evaluated the effectiveness of the mitigation in accomplishing these goals. The study measured success rates at the crossing structures and conducted a before-after-control-impact analysis to determine how well the mitigation contributed to an observed decrease in WVC. 

 

The research demonstrated that the mitigation helped to reduce WVC by over 90%. In addition, over 112,000 successful passages by mule deer were recorded at the seven structures with an overall success rate of 96%. Results confirmed the value of both the wildlife overpass and underpass designs in maintaining mule deer connectivity for all age and gender classes; and underscored the influence of mule deer distributions in crossing structure use, regardless of structure type. 

 

The study also established the value of the wildlife crossing structures for a number of other species, including ungulates, large carnivores, and meso and small mammals. While the total number of successful passages by other ungulate species was much lower than for mule deer, success rates were high across species. The research detected some species-specific preferences for underpasses versus overpasses and determined the primary influences on each species use of the crossing structures. 

 

This research was instrumental in demonstrating the success of the wildlife crossing structures and fencing mitigation for both wildlife and motorist safety. While a recent emphasis has been placed on migration paths in the western U.S., this research confirmed the need to also protect movements within winter range. Overall, the findings of this study and resulting recommendations will help transportation and wildlife agencies continue to site and design wildlife crossing mitigation systems for maximum success.

 
Behavioural Disparity in a Partially-Migratory Elk Herd on a Sympatric Winter Range
Madeline Trottier, Evelyn Merrill, Mark Hebblewhite

Sociality incurs costs and benefits for group-living animals, resulting in behavioural trade-offs, such as dominance, that may drive patterns of association among group members. We examined interaction patterns among elk in the partially migratory Ya Ha Tinda (YHT) elk herd (Cervus canadensis) in Alberta, Canada following three migratory tactics (residents; eastern migrants; western migrants). Because familiarity may influence dominance and thus group interactions, we predicted that familiarity would be higher within versus among migrant tactics, and thus 1) spatial overlap will be lower among versus within tactics, and 2) rates of interaction and aggression will differ among tactics. At the home range scale, we used GPS telemetry data to document home range overlap of collared female elk on the sympatric range during the winters of 2015-2018. We determined the volume of intersection (VI) of 95% utilization distributions (UD) during the winter between all tactics (resident-resident, resident-eastern, resident-western). Mean overlap was high (0.78 ± 0.013 SE) among all pair types, though resident-eastern overlap was higher (p < 0.005) than resident-western overlap (p < 0.005) compared to average resident-resident VI. At the individual level, we evaluated dominance from direct observations of conspecific interactions during winters 2019-2020 relative to migrant tactic, age, density, and time of year. Preliminary results suggest differences in aggression rates among migrant tactics, but similar rates of interaction overall (range 0.0031± 0.0005 - 0.0035 ± 0.0004 interactions/min.). We discuss the differences in dominance among migratory tactics and the effect of this on forage acquisition and predation risk. 

 
Resource Selection by a Mule Deer Population Following Pinyon-Juniper Removal
Jason Gundlach, Kelley M Stewart, Joe Bennett, Cody Schroeder

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.  Individuals were fitted with GPS collars to determine their response to this treatment.  Pinyon-juniper trees on mule deer winter range were delineated and removed by the U.S. Forest Service within a Before-After-Control-Impact experimental design, 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.  Through the duration of the study, changes in size and location of home ranges on winter range were quantified via movement based kernel density estimators.  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.

 
Resource Selection by Female Mule Deer and White-Tailed Deer in Western Kansas.
Talesha Karish, David Haukos, Andrew Ricketts, Levi Jaster

Mule deer (Odocoileus hemionus) abundance and occupied range have been declining in Kansas for greater than 20 years. During that same time white-tailed deer (O. virginianus) populations and range have been expanding. While it is unknown what is causing these declines, a predominant hypothesis for the loss of mule deer and concurrent expansion of white-tailed deer is adaptation of white-tailed deer to changes in land use and land cover as reflected in resource selection. Differences in resource selection between the species possibly allows white-tailed deer to have an indirect competitive advantage over mule deer. Our objective was to evaluate differences in seasonal multi-scale resource selection by female mule deer and white-tailed deer in western Kansas. A total of 184 females were captured and collared between two study sites with different land use and management practices. Each deer was fitted with a GPS satellite radio collar that recorded locations every hour for the life of the collar. Using those locations, we completed weekly micro-habitat vegetation surveys for used and random locations. Resource use by females was compared between a combination of annual seasons and reproductive stages. We used logistic regression to determine resource selection by females using macrohabitat and microhabitat variables from March through January for each year. Resource selection was assessed and compared between different spatial landscape scales, within total home range, and core area.  Preliminary results indicate white-tailed deer selected for canopy cover when it was available, whereas mule deer most consistently selected for steeper slopes. These results will be included in a larger assessment of how resource selection between these species and study sites may contribute to the differing population trends.

 
Female Elk Seasonal and Weekly Home Ranges and Habitat Use in Southwest Virginia
Braiden Quinlan, Shannon Bowling, Mark Ford, Michael Cherry

To inform elk (Cervus canadensis) management needs following their restoration on the central Appalachian landscape, biologists need space use and habitat utilization information. Using Virginia cow elk GPS location data from –southwest Virginia, 2012-2017, we created home ranges to quantify seasonal variation of cow space use and habitat selection We separated individual cow locations by four biological seasons– food scarcity (Dec. 1st – Mar. 15th), mid-late gestation (Mar. 1st – May 31st), calving (Jun. 1st – Aug. 31st), and harems (Sep. 1st – Nov. 30th), along weekly intervals within each season. Using these seasonal distinctions, we generated 95% minimum convex polygon home ranges for each cow whose locations encompassed the specified time intervals. We separated land cover into seven distinct types: Appalachian oak (Quercus spp.), cove/mixed mesophytic, pine (Pinus spp.), reclaimed surface mines, pasture and other non-mine open lands, developed, and water. At the coarser scale of biological season, mean home range size during the food scarcity period was significantly smaller (p <0.05) than any other season. Utilization of mine lands and other open habitats with cool season grasses predominated at this time. At the weekly scale, mid-late gestation home range sizes increased with an increase in use of oak and cove/mixed hardwood habitats. This was likely a result of both exploratory movements for sheltered parturition locations as well as spring green-up with increased herbaceous and woody forage availability in the forest. Reclaimed mines present a unique opportunity for restoring elk and associated early successional habitat contingent species in Appalachia. Our analysis shows that although female elk generally are associated with post-mined lands at the larger seasonal scale, finer temporal examinations reveal more varied habitat use.

Contributed Oral
Location: Virtual Date: November 2, 2021 Time: 2:00 pm - 3:00 pm