Browsing by Author "Miller, Karl V."

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    Behavioral response of white-tailed deer to coyote predation risk
    Gulsby, William D.; Cherry, Michael J.; Johnson, James T.; Conner, L. Mike; Miller, Karl V. (Ecological Society of America, 2018-03)
    Behavioral responses of prey to predation risk can affect lower trophic levels. White-tailed deer (Odocoileus virginianus; hereafter deer) increase vigilance in response to coyote (Canis latrans) presence, but vigilance responses to spatiotemporal variation in coyote abundance are unknown. Therefore, we examined the relationship between deer foraging behavior and coyote abundance on two 2000-ha study areas in Georgia, USA, during 2010-2013. We used baited camera traps during fall and winter to quantify deer behavior (i.e., feeding or vigilant) and estimated coyote abundance using fecal genotyping to noninvasively mark and recapture individuals. During 2011 and 2012, coyote removals were implemented on each study area. Coyote abundance (i.e., predation risk) varied spatiotemporally and was a predictor of foraging behavior during at least one season for all sex-age classes of deer except juveniles. Adult males were more sensitive to predation risk in winter, after the breeding season, whereas adult females were sensitive to predation risk during both seasons, but more so during fall when offspring are at greater risk. Yearling males were more sensitive to predation risk than adult males, and juveniles were least sensitive to predation risk, likely because of inexperience and high energetic demands. Reproductive chronology explained sex-specific and seasonal antipredator responses to predation risk, but there was a non-linear relationship between indirect predator effects and direct predation risk for some sex-age classes. Our results suggest deer detect and respond behaviorally to variation in coyote abundance. Due to the widespread distribution of deer and their interactions at multiple trophic levels, the ecological implications of this finding may be wide-reaching.
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    Breeding chronology and social interactions affect ungulate foraging behavior at a concentrated food resource
    Stone, David B.; Cherry, Michael J.; Martin, James A.; Cohen, Bradley S.; Miller, Karl V. (PLOS, 2017-06-07)
    Prey species must balance predator avoidance behavior with other essential activities including foraging, breeding, and social interactions. Anti-predator behaviors such as vigilance can impede resource acquisition rates by altering foraging behavior. However, in addition to predation risk, foraging behavior may also be affected by socio-sexual factors including breeding chronology and social interactions. Therefore, we investigated how time-of-day, distance-to-forest, group size, social interactions (presence of different sex-age class), and breeding chronology (pre-breeding, breeding, post-breeding seasons) affected probability of feeding (hereafter: feeding) for different sex and age-classes (mature males, immature males, adult females, and juveniles) of white-tailed deer at feed sites. We developed a set of candidate models consisting of social, habitat, reproductive, and abiotic factors and combinations of these factors. We then used generalized linear mixed models (GLMMs) to estimate the probability of feeding and used model averaging of competing models for multimodel inference. Each adult sex-age class’ feeding was influenced by breeding chronology. Juveniles were more likely to be feeding than adults in all seasons. Feeding increased with group size for all sex-age classes. The presence of a mature male negatively influenced the feeding of immature males and juveniles were more likely to be feeding when an adult female was present. Feeding decreased with increasing distance-to-forest for mature males but not for other sex-age classes. Our results indicate that each sex-age class modulates vigilance levels in response to socio-sexual factors according to the unique pressures placed upon them by their reproductive status and social rank.
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    Habitat selection and diurnal refugia of gray foxes in southwestern Georgia, USA
    Deuel, Nicholas R.; Conner, L. Mike; Miller, Karl V.; Chamberlain, Michael J.; Cherry, Michael J.; Tannenbaum, Larry V. (PLOS, 2017-10-17)
    Understanding habitat selection of gray foxes (Urocyon cinereoargenteus) is essential to evaluate their potential response to changes in land use and predator communities. Few studies have evaluated temporal habitat selection or explicitly identified habitats used by gray foxes for diurnal refugia. We used GPS collars to obtain location data for 34 gray foxes (20 males and 14 females) from February 2014 to December 2015 to evaluate temporal (seasonal and diel) habitat selection and selection of diurnal refugia in southwestern Georgia, USA. We analyzed habitat selection at 2 levels, selection of a core area within the home range and selection of locations within the home range. Habitat selection was non-random (P < 0.001) but consistent among seasons, between day and night, and between sexes (P > 0.05). Hardwoods, human use (i.e., areas associated with regular human activity such as buildings, lawns, parking areas, etc.), and roads were selected (P < 0.05), whereas pine dominated stands were used randomly (P > 0.05). Selection of habitats for diurnal refugia did not vary seasonally or by sex (P > 0.05), with foxes selecting (P < 0.05) areas near hardwood forests, roads, agriculture, human use, pastures/food plots, and shrub scrub habitats. Gray foxes were observed on the ground while resting, and we found no evidence of gray foxes diurnally resting in trees. Our results suggest that on our study area, gray foxes are an edge species that prefer forests with a hardwood component in areas near human use and roads.
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    Survival of White-Tailed Deer Neonates in Louisiana
    Shuman, Rebecca M.; Cherry, Michael J.; Simoneaux, Taylor N.; Dutoit, Elizabeth A.; Kilgo, John C.; Chamberlain, Michael J.; Miller, Karl V. (2017-07)
    Changing predator communities have potential to complicate management focused on ensuring sustainable white-tailed deer (Odocoileus virginianus) populations. Recent research reported that predation on neonates by coyotes (Canis latrans) and bobcats (Lynx rufus) can limit recruitment. However, no research has been conducted in areas of the southeastern United States with 3 sympatric neonate predators such as coyote, American black bear (Ursus americanus), and bobcat. Our objectives were to estimate neonate survival rates, identify causes of neonate mortality, and determine which biological and landscape characteristics were related to neonate survival. During 2013-2015, we captured 70 neonates with the aid of vaginal implant transmitters on Tensas River National Wildlife Refuge in northeastern Louisiana, USA. We monitored neonates every 8 hours until 6 weeks of age and daily until 12 weeks of age, and assigned cause of death from field and DNA evidence. Survival of neonates to 12 weeks was 0.271 (95% CI=0.185-0.398). Of 51 mortalities, 45 (88%) were attributed to predation, 4 (8%) to starvation, 1 (2%) to other causes, and 1 (2%) to unknown causes. We used an information-theoretic approach to compare Cox proportional hazards models containing various combinations of biological and habitat covariates. Our best-supported model contained sex, mass at birth, distance to cropland, young reforestation (planted 2000-2009), and old reforestation (planted 1980-1989). Based on hazard ratios, survival was 81% higher for males than females, and survival increased 81% with every 1-kg increase in birth mass. Survival increased 8% for every 100-m increase in distance from cropland or young reforestation, and decreased 11% with every 100-m increase in distance from old reforestation, which may be a result of spatial variation in predator distribution. Our results emphasize the importance of site-specific monitoring of neonate recruitment rates in areas with burgeoning predator communities. We conclude, however, that although predation pressure was high, survival rates were similar to those observed in 2-predator systems in the region, suggesting the possibility that an upper limit to predation rates may exist for white-tailed deer neonates. (C) 2017 The Wildlife Society.