Conservation and Ecology of Mammals – Cervids III

Contributed Paper
ROOM: Rooms 27 – Picuris, 29 – Sandia and 31 – Santa Ana Combined
SESSION NUMBER: 92
 

10:30AM White-tailed Deer Fawn Space Use in Central Iowa
Patrick G. McGovern; Julie A. Blanchong; Stephen J. Dinsmore
White-tailed deer (Odocoileus virginianus) are habitat generalists that thrive in the agricultural landscape of the Midwest where permanent cover is limited, but food is abundant. The value of agricultural habitat to deer, however, might be different for adult versus young animals. Specifically, while adults make use of crops as an abundant food source, young fawns rely on nursing and require cover to minimize their vulnerability to predation. We hypothesized that young fawns would avoid using agricultural habitat and instead spend the majority of their time in wooded habitat. To test our hypothesis, we estimated home range size and habitat composition for fawns in central Iowa during their first three months of life. We captured and radio-collared 36 white-tailed deer fawns in May-June 2015 – 2016 in Boone County, Iowa, USA. We located fawns ≥5 times a week through August and created 95% kernel density home ranges for fawns with >30 locations (n=27). Fawn home ranges at three months of age averaged 25.67 ha (SE=2.43) and were comprised primarily of woodland (61.66% [4.77]) and grassland (22.77% [3.18]) habitat. Home range size and habitat composition were not significantly different between years or sexes. Fawns displayed third-order habitat selection (λ=0.07, P=0.002), using significantly less agriculture and wetland habitat and fewer roads compared to their availability in their home ranges. Early in life, fawns avoid predation primarily by hiding. Early summer row-crop agricultural habitat is unlikely to provide sufficient cover for fawns. Our findings suggest that agricultural habitat is not of value to young fawns and that maintenance of woodland habitat in agriculturally dominated landscapes is important.
10:50AM Evaluating The Influence of White-tailed Deer on Forest Regeneration at Landscape Scales In New York
David W. Kramer; Mark Lesser; Rachel Wheat; Martin Dovciak; Jeremy E. Hurst; Jaqueline Frair
White-tailed deer (Odocoileus virginianus) herbivory can have significant lasting effects on woody regeneration in northern forests. In the state of New York, white-tailed deer populations increased dramatically during the second half of the 20th century, greatly increasing browse related impacts on forests throughout the state. Studies suggest that reductions in localized browsing pressure can positively influence the abundance and survival of woody stems in forested stands, therefore we hypothesize that reductions at regional or statewide deer populations can improve woody regeneration in forested stands in the state of New York. To evaluate our hypothesis, we predicted regenerating stem abundance from statewide Forest Inventory Assessment (FIA) as a function of local seed rain, forest type and stand characteristics, landscape heterogeneity, and regional deer abundance. We developed a candidate set of non-linear models and used Akaike information criterion to determine which variables impacted ten abundant tree species. The impact of covariates varied among tree species, with the exception of species-specific canopy abundance which was consistently found to have both a positive linear effect and a negative nonlinear in the top model for each species. Deer abundance was found to impact all of the ten woody species, however the trend of the effect varied across species. Moreover, herbivory effects varied with geographical distribution in nine of the ten species. We applied the top models to set optimal silvicultural conditions and then simulated the effects of decreasing deer density at management-relevant scales to observe predicted changes in regeneration success of each of the study species. Managers can use these models to identify areas in which increases of species-specific regeneration are both necessary and assess the degree to which target increases can be achieved through deer herd reductions.
11:10AM Seasonal Effects of Coyote Abundance on White-tailed Deer Foraging Behavior in the Georgia Piedmont
William D. Gulsby; Michael J. Cherry; James T. Johnson; L. Mike Conner; Karl V. Miller
Coyotes can reduce white-tailed deer fawn recruitment, but coyote effects on deer foraging behavior has received less attention. Because antipredator behaviors, including reduced time spent feeding, may affect fitness, we examined the effect of experimentally manipulated coyote abundance on deer foraging behavior on two central Georgia WMAs during 2010-2012. We estimated annual coyote abundance for each WMA with a capture-recapture design using data from genotyped coyote scats collected along established transects. We measured deer foraging behavior using fall and winter camera surveys concurrent with coyote abundance monitoring. We categorizing deer in photos as feeding or not and used generalized linear mixed models to examine the effects of coyote abundance and social factors on probability of feeding for adult and yearling males, adult females, and fawns. Yearling males and adult females decreased feeding with increasing coyote abundance during fall and winter. Adult males decreased feeding with increased coyote abundance in the winter, but not during fall. For adult females and fawns, feeding was positively associated with group size and negatively associated with the presence of males. Coyote abundance influenced age-sex classes differently, thus our study supports the hypothesis that predation risk enhances behavioral differences and segregation among the sexes. Our results suggest that reducing coyote abundance can increase the efficiency with which deer forage. Future studies should investigate whether the behavioral responses to variation in predator abundance can influence individual fitness (e.g., fecundity, body mass) within deer populations.
11:30AM Sociality of Adult Female White-tailed Deer Following Parturition
Jacob M. Haus; Jacob L. Bowman; Justin R. Dion; Joseph E. Rogerson
Female white-tailed deer (Odocoileus virginianus) typically form matriarchal social groups throughout much of the year, however little research has examined the effect of parturition on sociality. We used dynamic interaction, a function of travel direction and displacement, to examine social interactions between adult female deer during parturition. We captured 10 free-range adult does (2.5 – 5.5 years at capture) on a 123 ha section of private property in south central Sussex County, Delaware. We fit all does with a vaginal implant transmitter and an iridium GPS collar equipped with NeoLink technology. Collars were programmed to take 1 fix/hour from 1 May to 31 June 2016. We calculated a local (di) and global (DI) dynamic interaction metric for all does with overlapping 95% kernel density home range estimates, and average proximity (m) for all does with non-overlapping ranges. Area of home range overlap (km2) was positively correlated with global DI (p < .01). We centered local di values on the hour of parturition for each doe interaction and averaged across the population. Prior to parturition, average local di was approximately 0.25, indicating moderate group cohesion. Following parturition, average local di values declined below 0.0, suggesting possible avoidance among does with overlapping ranges. Average local di began to increase at approximately 14 days post-parturition, but did not return to pre-parturition levels during our study period (~25 days post-parturition). We observed no temporal effect on average proximity among does with non-overlapping ranges; however, 2 individuals made extra range movements to birth sites. Our results suggests that adult does maintained social cohesion until parturition, avoided interaction until 2 weeks post-parturition, and then slowly integrated back into social groupings. The delay in reformation of social groups is likely a function of neonate mobility and predator avoidance.
11:50AM Landscape-Level Patterns in White-tailed Deer Fawn Survival in North America
Tess Gingery; Duane Diefenbach; Bret D. Wallingford; Christopher S. Rosenberry
We conducted a meta-analysis of white-tailed deer (Odocoileus virginianus) fawn survival and cause-specific mortality across North America to identify broad-scale biotic factors related to this population parameter. We used published data from 27 populations on fawn survival rates that reported a survival rate for fawns that lived to 3–6 months, sample size, landscape description, deer density, and cause-specific mortality. We included survival estimates for fawns from birth to 3–6 months of age because most mortality occurs within 8 weeks of birth. We used linear models to investigate the relationship of fawn survival to landscape-level land use and to deer density. We classified cause-specific mortality as human-caused, natural (excluding predation), and predation and estimated the proportion of these causes in agriculturally dominated, forested, and mixed landscapes. Survival to 3–6 months of age was 42.3% in contiguous forest landscapes (no agriculture) and for every 10% increase in agricultural land area fawn survival increased 4.8% (n = 12, SE = 0.12). We failed to detect a relationship between fawn survival and deer density (n = 13, P = 0.82). Habitats with mixed forest and agricultural landscapes had greater proportions of human-caused mortalities, and proportionally less mortality due to predators, than either forested or agriculturally dominated landscapes (n = 22, Ps ≤ 0.01). The proportion of natural deaths did not differ among mixed, forested, and agricultural landscapes even though overall mortality rates differed (P = 0.08). Fawn survival studies that focus on factors affecting fawn susceptibility to mortality, and report habitat composition and predator population information, will enhance the ability of meta-analyses to detect patterns not evident from individual population studies.

 

Contributed Paper
Location: Albuquerque Convention Center Date: September 27, 2017 Time: 10:30 am - 12:10 pm