Big Game II

Contributed Oral

Long-Term Post-Fire Vegetation Response Influences Mule Deer Survival
Elizabeth Schuyler, Lisa Ellsworth, Dana Sanchez, Don Whittaker

Decades of wildfires and subsequent invasion of non-native annual grasses, combined with extensive fire suppression followed by widespread juniper expansion, have led to dramatic changes in sagebrush ecosystems occupied by mule deer (Odocoileus hemionus). Habitat loss and degradation influence the quantity and quality of available forage, which can negatively influence adult survival. We used known-fate data for 111 radio-collared female mule deer to estimate monthly survival rates and to investigate factors that may affect these rates such as movement behavior (migratory or resident) and habitat characteristics (wildfire, juniper canopy cover, summer plant productivity) in areas supporting sagebrush Potential Vegetation Type (PVTs) as common mule deer habitats. The dataset included 116,421 GPS location points from 2015-2017 in the John Day Basin, Oregon, USA. Time since fire was a strong predictor of mule deer survival which differed based on season and the underlying PVTs. Survival was negatively associated with burned areas (16-20 yr-old) in Wyoming big sagebrush PVTs in an individual’s winter range (Dec-Feb). Conversely, survival was positively associated with burned areas (11-15 yr-old) in an individual’s summer range (Jun-Aug) in dry forest PVTs and western juniper PVTs. Annual survival (0.79) was low compared to survival rates for adult female mule deer in other parts of their geographic range. These findings demonstrate how post-fire vegetation response in different PVTs can influence mule deer population dynamics a decade or longer following a wildfire.

Risk Averse Vs Risk Prone Tradeoffs Associated with Reproduction in a Large Mammal
Marcus Blum, Kelley M Stewart, Kevin Shoemaker, Ben Sullivan, brian wakeling, Mike Cox, Vern Bleich

Animals select habitats based on 4 key components, water, food, space, and cover.  Each of these components are essential to an individual’s ability to reproduce, survive, and therefore enhance that individual’s reproductive fitness.  Additionally, individuals may partake in habitat trade-offs to positively influence their reproductive fitness.  We were interested in investigating the potential for risk averse vs risk prone trade-offs associated with parturition seasons.  We used a population of desert bighorn sheep (Ovis canadensis nelsoni) to investigate the potential for these trade-offs during parturition periods.  We captured 32 female bighorn sheep at Lone Mountain, Nevada from 2016 to 2018.  Individuals were fit with GPS satellite collars, tested for pregnancy status, and implanted with vaginal implant transmitters.  Furthermore, we collected fecal samples throughout parturition periods to identify diet quality and composition during these time periods.  We estimated differences in selection between females provisioning and not provisioning offspring, as well as the length of time it took for females with offspring to return to pre-parturition levels of selection using a Bayesian hierarchical model.  Our results indicated shifts in habitat selection, associated with provisioning status of females.  Females selected for more rugged terrain, less steep slopes, and higher shrub and tree cover cover when provisioning offspring.  Furthermore, females provisioning offspring displayed varying rates of return to pre parturition levels of selection, indicating that age of juveniles influenced selection of habitat characteristics.  Additionally, we found clear shifts in diet quality associated with provisioning status.  Females that were provisioning offspring had lower quality diets than those that were not provisioning offspring.  These results show clear shifts in selection strategies associated with provisioning of offspring, in addition to tradeoffs associated with reproduction when combined with diet data from this population.

Biological and Environmental Factors Affecting Postpartum Movement in White-Tailed Deer
Angela Holland, Justin Dion, Jacob Bowman

Movement behavior of female white-tailed deer (Odocoileus virginianus) during lactation is influenced by increased nutritional need and availability of hiding cover for fawns.  Others have hypothesized that social standing of older females results in increased habitat quality and therefore increased nutrition within their home range which in turn may explain why fawns of older age individuals have increased survival rates. Our objective was to determine if biological factors such as doe age, fawn age, and number of fawns as well as characteristics of prepartum home range affected the postpartum daily movement or home range overlap.  We collected GPS locations 2 weeks pre- and postpartum on 22 female white-tailed deer in Sussex County, Delaware (2,420 km2).  We used a hierarchical modeling process to test biological factors and prepartum home range characteristics on two aspects of postpartum movement behavior, average daily step length and daily percent overlap with prepartum home range.  When using a linear mixed effects model with individual doe as a random effect, average daily step length decreased with increased doe age and increased with litter size and the does home range size prior to parturition.  We found that increased fawn age increased overlap with prepartum home range when using a logistic mixed effects model with individual doe as a random effect.  Our results indicate that younger does are moving more than older does during lactation potentially to access higher quality habitat.  This increased movement increases nutritional demand and may play a role in fawn survival.  Does are more likely to use more of their prepartum home range as fawns age, a finding congruent with previous research.

Evaluation of Expandable GPS Collars and Behavioral Impacts on White-Tailed Deer Fawns
Zachary Wesner, Andrew Norton, Tyler Obermoller, David Osborn, Gino D’Angelo

Integrating Global Positioning System (GPS) technology with expandable collars will allow researchers to more accurately investigate survival of white-tailed deer (Odocoileus virginianus) fawns. We tested fit and function of 5 expandable GPS collar mock-up designs on white-tailed deer fawns and conducted focal observations to determine potential impacts on behavior at the Whitehall Deer Research Facility, Athens, GA, USA during 2018–2020. We fitted 46 fawns with collars and ear-tagged 15 control fawns without collars. We used hierarchical logit and multinomial generalized linear models to estimate parameters and evaluated differences among collar type groups using an information theoretic approach. Fawns retained Telonics v1.0 and v2.0 collars for a mean 101 (±46 [SD]) and 70 (±37) days, respectively. Fawns retained Vectronic v1.0 and v2.0 collars for a mean 246 (±156) and 306 (±99) days, respectively. Vectronic collared fawns were 1011% more likely to be bedded than uncollared fawns during the first 4 weeks. Bedded fawns with Vectronic (v1.0 and v2.0) and Telonics v2.0 collars were 20–41% more likely to exhibit a tucked head position and 2242% less likely to have their head up than uncollared fawns during the first 4 weeks. Collared fawns were also 18–26% more likely to exhibit a head tilt than uncollared fawns. Vectronic (v1.0 and v2.0) and Telonics v2.0 collared fawns were 2442% less vigilant and slept 2548% more than uncollared fawns during the first 4 weeks. Uncollared and Vectronic collared fawns increased activity and alertness across 12 weeks, while activity and alertness of Telonics collared fawns decreased. We detected no other important differences in behavior (e.g., suckling, grooming) between collared and uncollared fawns. GPS collar designs we evaluated would benefit from modifications before field use, including improved stitching patterns and threads, smaller batteries, improved weight distribution, and smaller band circumferences.

Spring Phenology Drives Range Shifts in a Migratory Arctic Ungulate with Key Implications for the Future
John P. Severson, Heather Johnson, Stephen Arthur, William Leacock, Michael Suitor

Annual variation in phenology can have profound effects on the behavior of animals. As climate change advances spring phenology in ecosystems around the globe, it is becoming increasingly important to understand how animals respond to variation in the timing of seasonal events and how their responses may shift in the future. We investigated the influence of spring phenology on the behavior of migratory, barren-ground caribou (Rangifer tarandus), a species that has evolved to cope with short Arctic summers. Specifically, we examined the effect of spring snowmelt and vegetation growth on the current and potential future space-use patterns of the Porcupine Caribou Herd (PCH), which exhibits large, inter-annual shifts in their calving and post-calving distributions across the U.S.-Canadian border. We quantified PCH selection for snowmelt and vegetation phenology using machine learning models, determined how selection resulted in annual shifts in space-use, and then projected future distributions based on climate-driven phenology models. Caribou exhibited strong, scale-dependent selection for both snowmelt and vegetation growth. During the calving season, caribou selected areas at finer scales where the snow had melted and vegetation was greening, but within broader landscapes that were still brown or snow covered. During the post-calving season, they selected vegetation with intermediate biomass expected to have high forage quality. Annual variation in spring phenology predicted major shifts in PCH space-use. In years with early spring phenology, PCH predominately used habitat in Alaska, while in years with late phenology, they spent more time in Yukon. Future climate conditions were projected to advance spring phenology, shifting PCH calving and post-calving distributions further west into Alaska. Our results demonstrate that caribou selection for habitat in specific phenological stages drive dramatic shifts in annual space-use patterns, and will likely affect future distributions, underscoring the importance of maintaining sufficient suitable habitat to allow for behavioral plasticity.

Summer Recreational Trail Influence on Elk in the Gunnison Basin
Chloe Beaupre, Alissa Bevan, Jessica Young, Kevin Blecha

With continual growth in recreational trail use, it is becoming increasingly complicated to balance demands for outdoor recreation opportunities with wildlife habitat conservation. To better understand how Rocky Mountain elk respond to trails, this project deployed remote cameras to determine ungulate usage responses with regards to various trail parameters. We deployed 118 cameras in a paired study design throughout the upper Gunnison Basin of southwest Colorado in the summer of 2020. Each on-trail camera was paired with an off-trail camera, at a gradient of distances away from the trail. Habitat characteristics within pairs were matched using 12 landscape variables to control for other variables known to influence ungulate distribution so that only trail proximity differed between on and off-trail cameras. Paired cameras provided a comparison of animal encounters on and off-trail, while the on-trail camera yielded recreation traffic counts to assess how animals respond to varying amounts of traffic for each camera pair.

Our cameras showed a higher likelihood of encountering elk as a function of increasing Euclidean distance to trails. An interaction between Euclidean distance and traffic volume showed elk respond negatively to increased traffic at closer distances to trails while higher recreation volumes corresponded with an increase in elk encounters at the farther distances. Despite our methodology using remote cameras to measure both trail traffic and ungulate responses simultaneously being fairly novel, these results are consistent with the literature. Other published studies have demonstrated GPS collared elk avoid human traffic and similarly reflect the importance of security areas away from trails. With outdoor recreation increasing throughout the mountain west, our results underscore the need for strategic trail planning (i.e. reducing trail network sprawl) and the value of ample security habitat for elk.

Future Altered Plant Phenology Projected to Reduce Benefit of Migraton for Mule Deer
Tabitha Graves, Ethan Berman, Sarah Dewey, Ellen Aikens, Troy Fieseler, Aaron Johnston, Matthew Kauffman, Jerod Merkle, Kevin Monteith, Jill Randall, Imtiaz Rangwala, David Wood
Climate influences on forage phenology may lead to future changes in the benefits of migration as animals follow the pattern of highly nutritious vegetation green-up in the spring. Ungulates with high site fidelity to migration routes, such as mule deer, may be among the species most influenced by changes in phenology. We evaluated the drivers of two key land surface phenology metrics most tied to spring migration patterns, the peak instantaneous green up date (PIRGd) and the length of the peak period of spring green-up (spring scale) across Wyoming. We then projected future phenology metrics at mid (2040-2069) and end of century (2070-2099) to better understand impacts of future phenology on ungulates, considering 2 emissions scenarios (RCP 4.5 and 8.5) and 5 global climate models (GCM) bracketing projected future conditions in temperature and precipitation. We also projected future metrics annually for the middle GCM. Models for PIRGd and spring scale included covariates related to both temperature and precipitation. We projected earlier PIRGd and longer spring scale with longer spring scale under drier conditions. Across 210 spring mule deer migration routes, representing herds spanning most of western Wyoming, our projections indicated the duration and order of migration rates would likely decrease, while the spring scale would increase. This pattern is expected to be less beneficial for migrating mule deer, which could lead to a decline in the proportion of migrating deer. If alternate migration routes do not counteract this pattern and local forage resources limit resident mule deer abundance, over time a decline in the number of mule deer is possible. This research provides an approach for projecting climate change effects on important aspects of ungulate ecology and useful information for biologists to plan habitat treatments, consider effects of energy developments, prioritize land conservation and manage big game populations.
Offering a Counterview of White-Tailed Deer: Abundance, Benefits, and Open Forests
Brice Hanberry

The prevailing view is that white-tailed deer (Odocoileus virginianus) are overabundant, damaging to vegetation and society, and an edge species. To offer a counterview, evidence is not available to demonstrate deer populations are outside of historical bounds, damage to vegetation likely is less than in the past when multiple large vertebrate herbivores existed, deer are beneficial to ecosystems and society, and deer are species of open forests, which contain both woody and herbaceous resources. Nonetheless, deer have adjusted well to current landscapes with spatially disjunct resources that occur at the juxtaposition of closed successional forests and clearings. I modeled deer densities and land classes, using random forests and extreme gradient boosting classifiers, which substantiated that deer occurred at greater densities in deciduous forests and lower densities in agricultural and residential development. Deer provide important socioeconomic and ecological services as the most economically valuable species that supports wildlife agencies, ecological ambassadors, and by a natural disturbance to reduce number of small trees, particularly in the absence of surface fire disturbance.

Contributed Oral
Location: Virtual Date: November 5, 2021 Time: 2:00 pm - 3:00 pm