Charles Ruth

Can Coyotes Affect Deer Populations in Southeastern North America

Abstract The coyote (Canis latrans) is a recent addition to the fauna of eastern North America, and in many areas coyote populations have been established for only a decade or two. Although coyotes are known predators of white-tailed deer (Odocoileus virginianus) in their historic range, effects this new predator may have on eastern deer populations have received little attention. We speculated that in the southeastern United States, coyotes may be affecting deer recruitment, and we present 5 lines of evidence that suggest this possibility. First, the statewide deer population in South Carolina has declined coincident with the establishment and increase in the coyote population. Second, data sets from the Savannah River Site (SRS) in South Carolina indicate a new mortality source affecting the deer population concurrent with the increase in coyotes. Third, an index of deer recruitment at SRS declined during the period of increase in coyotes. Fourth, food habits data from SRS indicate that fawns are an important food item for coyotes during summer. Finally, recent research from Alabama documented significant coyote predation on fawns there. Although this evidence does not establish cause and effect between coyotes and observed declines in deer recruitment, we argue that additional research should proactively address this topic in the region. We identified several important questions on the nature of the deer–coyote relationship in the East.

Factors Influencing Survival of White-tailed Deer Fawns in Coastal South Carolina

Abstract The social and environmental pressures exerted on white-tailed deer Odocoileus virginianus in the southeastern United States are dynamic. Understanding factors that contribute to neonatal white-tailed deer mortality is vital to population management. To determine survival rates and causes of mortality, we captured and radio-monitored neonate white-tailed deer in the coastal plain of South Carolina. Using date of birth, mass, sex, age, and year as predictor variables, we created a candidate set of survival models to evaluate which factors influenced daily survival rates. We captured and monitored 210 fawns and recorded 68 total mortalities (32.3%). We recorded few mortalities in 2006 (n  =  5; 12.8%) and 2007 (n  =  5; 12.5%), but we observed a significant increase in mortality in 2008 (n  =  18; 37.5%), 2009 (n  =  28; 53.8%), and 2010 (n  =  12; 38.7%). Predation accounted for the majority of mortalities (n  =  29; 42.6%). We found that male fawns were more than twice as likely to survive as fem...

Are camera surveys useful for assessing recruitment in white-tailed deer?

Camera surveys commonly are used by managers and hunters to estimate white-tailed deer Odocoileus virginianus density and demographic rates. Though studies have documented biases and inaccuracies in the camera survey methodology, camera traps remain popular due to ease of use, cost-effectiveness, and ability to survey large areas. Because recruitment is a key parameter in ungulate population dynamics, there is a growing need to test the effectiveness of camera surveys for assessing fawn recruitment. At Savannah River Site, South Carolina, we used six years of camera-based recruitment estimates (i.e. fawn:doe ratio) to predict concurrently collected annual radiotag-based survival estimates. The coefficient of determination (R2) was 0.445, indicating some support for the viability of cameras to reflect recruitment. We added two years of data from Fort Bragg Military Installation, North Carolina, which improved R2 to 0.621 without accounting for site-specific variability. Also, we evaluated the correlation between year-to-year changes in recruitment and survival using the Savannah River Site data; R2 was 0.758, suggesting that camera-based recruitment could be useful as an indicator of the trend in survival. Because so few researchers concurrently estimate survival and camera-based recruitment, examining this relationship at larger spatial scales while controlling for numerous confounding variables remains difficult. Future research should test the validity of our results from other areas with varying deer and camera densities, as site (e.g. presence of feral pigs Sus scrofa) and demographic (e.g. fawn age at time of camera survey) parameters may have a large influence on detectability. Until such biases are fully quantified, we urge researchers and managers to use caution when advocating the use of camera-based recruitment estimates.

Breeding behavior of female white-tailed deer relative to conception: Evidence for female mate choice

Abstract Female white‐tailed deer (Odocoileus virginianus) are thought to choose between two behavioral strategies to maximize the quality of potential mates: sit and wait, characterized by concentrating activity within a restricted area, and excursive behavior, characterized by increased activity and excursions outside the home range. As movement patterns may influence conception, our goal was to examine the patterns of female white‐tailed deer movements to evaluate which breeding strategy was employed. We equipped 36 female white‐tailed deer with GPS collars from August 2013 to December 2015. We found that movement rate and probability of activity were greatest near the peak of the breeding season, and we observed increases in both metrics during the 40 days prior to estimated conception. Peak size of home range and core area occurred in the days surrounding conception. We found that 11 deer performed an excursion, ranging from 43 days before until 36 days after conception, with the peak probability of being outside of an individual home range occurring 1 day prior to conception. Our results suggest that female white‐tailed deer may attempt to maximize the quality of their mates by advertising availability for breeding through excursive behaviors just prior to entering estrus.

Recognizing the danger zone: response of female white-tailed to discrete hunting events

The landscape of fear theory proposes that prey should utilize habitat over space and time such that demographic risk is minimized. White-tailed deer Odocoileus virginianus respond to temporally and spatially predictable threats posed by humans consistent with the landscape of fear theory. However, few studies examining the response of deer to hunting have accounted for the localized nature of risk. To determine if white-tailed deer are able to recognize and respond to risks posed by hunters relative to specific hunting locations, we equipped 38 female white-tailed deer with GPS collars August–December 2013–2015. Deer were generally found to increase use of feeders, food plots, and vulnerability zones during crepuscular and nocturnal periods as the hunting season progressed. However, deer use of areas around hunting stands decreased during the middle of the day and increased at night in the days immediately following a stand being hunted. We detected no change in use of areas around hunting stands during crepuscular hours in days following when a stand was hunted. Our results suggest that female white-tailed deer are able to recognize and respond to localized risks and do so with a gradient of responses based on localized risk history. However, response was only apparent when analysis accounted for the localized nature of risk, suggesting previous studies may have underestimated the ability of deer to respond to such threats.