Survival of white‐tailed deer neonates in Louisiana

Abstract

ABSTRACTChanging 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. © 2017 The Wildlife Society.