White-Tailed Deer I

Contributed Paper
ROOM: CC, Room 25A

8:10AM Adapting Conventional Density Estimation Techniques to Monitor White-Tailed Deer
Sara Hansen; Ilai Keren; Jerry Nelson
White-tailed deer (Odocoileus virginianus) are an ubiquitous part of the landscape in eastern Washington and, though common, are notoriously difficult to monitor. Because of this, monitoring efforts in Washington have been largely restricted to rough population indices from road-based surveys. While similar to monitoring in many states, the Washington Department of Fish and Wildlife identified the need for more robust techniques able to provide defensible, baseline population data for management decisions. We tested the utility of an aerial-based mark-recapture distance sampling (MRDS) approach to provide representative coverage and account for detection biases due to distance and imperfect detection on the survey line. However, for aerial distance sampling to be effective for a small-bodied and flight-prone species like white-tailed deer, we first needed to account for assumptions of accurate measurement of distance to an animal, and that animals are detected at their original location. Our objectives were to determine the ability of new technology to accurately estimate location of and distance to detected animals such that observers would not need to leave the flight line to record a location, and implement a pilot survey to test movement response of deer under field conditions. We used a wireless laser rangefinder and tablet setup to test accuracy of locations recorded for 40 known-location targets along a simulated transect. We then conducted a pilot survey using an MRDS approach to determine deer movement away from the flight line. The rangefinders allowed us to quickly and accurately (<25 m error) acquire the location for each target, and subsequent deer group detected, without leaving the flight line. This approach reduced time needed to complete each transect and limited potential movement responses by deer farther down transect. The smooth shoulder of the resulting detection function indicated no movement of deer away from the aircraft prior to detection.
8:30AM Spatial and Temporal Variations in White-Tailed Deer Abundance and Detectability Across a Heterogeneous Landscape of Fear
Jennifer Kilburn; Tracy A.G. Rittenhouse; Andrew LaBonte; Howard Kilpatrick
Hunters, like other predators, create a heterogeneous landscape of fear where prey can reduce the risk of predation by modifying their behavior or space use. The recent rise in private protected open space (i.e., places accessible to the public, yet often closed to hunting) and their proximity to hunted properties may allow for them to act as refuge on the landscape. Understanding the degree to which these properties serve as refuge areas, and how refuge use might affect spatial variability in white-tailed deer abundance and detectability both seasonally and year-round is important to deer management. We used N-mixture models and 50 wildlife cameras to estimate abundance and detection probability and monitor trends in relation to the hunting season. We also fit kernel density functions to activity data and used the Wald’s test to determine if daily activity patterns differed between sites and across seasons. Estimates of abundance suggest that it is unlikely that deer are shifting to places closed to hunting, with a 44.21% probability of a shift in abundance in year one and a 42.98% probability of a shift in abundance in year two. Yet, we found a 70.03% probability that detection was higher on un-hunted sites compared to hunted sites during the hunting season in year one. This result along with lower activity on hunted sites compared to un-hunted sites in year one (0.16, SE=0.047) and a reduction in activity during the hunting season in year one (-0.13, SE=0.06) support a behavioral response to the hunting season. Patterns were less evident in year 2. While we did not find evidence of space use changes in response to hunting, our observed changes in detectability during hunting seasons and decreases in daily activity levels are evidence that deer use temporal and behavioral responses to avoid being predated by hunters.
8:50AM Foraging Behavior of White-Tailed Deer in Response to an Indicator of Coyote Presence in a Suburban Forest Preserve
Gretchen Anchor; Shane McKenzie; Chris Anchor; Stanley Gehrt
In recent decades, white-tailed deer (Odocoileus virginianus) and coyotes (Canis latrans) have spread into metropolitan and suburban areas of the United States. In the Chicago region, these species share the landscape and have a specific predator-prey relationship. Coyotes in the Chicago region rarely hunt adult deer but actively prey on fawns. Little is known about how this relationship influences the behavior of deer in suburban areas. Previous studies on adult deer behavior in relation to coyotes in urban and suburban areas failed to consider the potential habituation that can result from lack of predation. Our study examined how the predator-prey relationship exhibited in the Chicago region influences the foraging behavior of deer. We hypothesized that deer behavior would reflect the actual predation risk in suburban areas. Thus, we predicted, that increased vigilance and decreased visitation would be exhibited only by female adult deer with fawns, if at all. In 2017, we used camera traps to record deer behavior at bait stations before and after the introduction of coyote urine that we topically sprayed near food blocks. In months of increased fawn predation risk (late spring through summer) it was found that the number of visits and individual deer that utilized the test sites decreased after the introduction of coyote urine by 50% and 44%, respectively, with no observed pattern in low predation risk months. There wasn’t, however, a significant difference in behavior change after coyote urine administration between sexes or age classes. We also monitored fawn mortality concurrent to the foraging survey and in previous years using VHF-collars. For the summer 2017 season, 66.7% of fawn mortalities (42.9% of the total study fawns) were the result of coyote predation (33.3% unknown cause). These results support the idea that foraging behavior is influenced by actual predation risk.
9:10AM Stress Profiles for White-Tailed Deer Wintering in the Western Upper Peninsula of Michigan
Grace Parikh; Christopher R. Webster; John A. Vucetich; John J. Durocher; Joseph K. Bump
Seasonal movement of animals in response to changes in abiotic and biotic conditions can result in physiological stress. For white-tailed deer (Odocoileus virginianus) in regions with deep persistent snow packs, migration to winter “yarding” areas and associated aggregation can present a host of physiological trade-offs. These include benefits, such as concentrated activity in habitat with low snow depth (dense conifer habitats), ease of movement along deeply incised trails, and predator avoidance and enhanced vigilance, and costs, such as increased competition for limited food resources, and behavior stress and aggression. We investigated how deer abundance and landscape context interact to influence diet and physiological stress. Chronic stress can cause immunosuppression and reduced reproductive output, which can have consequences for individual survival and population recruitment, due to continual diversion of energy from vital functions. Specifically, we sought to obtain a spatial snapshot of stress based on fecal corticosterone in white- tailed deer at 7 winter yarding sites in the western Upper Peninsula of Michigan, and assess relationships with localized deer density as indicated by pellet group density, diet composition (based on microhistology), snow depth, and landscape characteristics. Fecal corticosterone was measured using an enzyme-linked immunosorbent assay (ELISA). We hypothesized that stress would initially decrease with increasing deer abundance, but increase as competition for resources and behavioral stress became more important at higher levels of deer abundance. Preliminary results from 48 individual fecal pellet samples in 2017 supported our hypothesis that stress would be lower at moderate deer densities than at higher or lower densities. Additional analyses to be presented will examine the relationship between stress and abiotic conditions (snow depth and duration) and landscape context. Our initial results highlight potential trade-offs made by wintering deer in a region subject to a suite of challenging conditions.
9:30AM Late Winter Survival of Adult Female White-Tailed Deer in Northern Michigan: Influence of Biological and Environmental Conditions.
Todd M. Kautz
A relationship between winter weather and survival of northern ungulates has long been established, yet the possible roles of biological (e.g., nutritional status) and environmental (e.g., weather) conditions make it important to determine which potential limiting factors are most influential. Our objective was to examine the potential effects of individual (body mass and age) and extrinsic (winter severity, snow depth, and snow melt date) factors on the magnitude and timing of mortality for adult (>2.5 years old) female white-tailed deer (Odocoileus virginianus) during February-May in the Upper Peninsula of Michigan, USA. We captured and monitored 150 deer during 2009-2015 in 2 areas with varying snowfall. February-May survival ranged from 0.24-0.89 (mean = 0.69) across years. Mortality risk increased 1.7% with each unit increase of cumulative winter severity index, decreased 7.2% with each cumulative snow free day, and decreased 11.9% with each kg body mass greater than the population average. Age and weekly snow depth did not influence deer survival. Predation, primarily from coyote (Canis latrans) and wolves (Canis lupus), accounted for 78% of known-cause mortalities. Our results suggest that deer condition entering winter and cumulative winter severity impact deer winter survival, but the timing of spring snow melt was the most influential factor determining late winter mortality in our study. This supports the hypothesis that nutrition and energetic demands from weather conditions drive northern ungulate winter ecology, and northern deer winter survival strategy is primarily based on enduring a negative energy budget. Under this model, a delay of several weeks in the timing of spring snow melt could exert a large influence on deer survival, resulting in a survival bottleneck.


Contributed Paper
Location: Cleveland CC Date: October 8, 2018 Time: 8:10 am - 9:50 am