Cause-Specific Neonatal Mortality of White-Tailed Deer in Wisconsin, USA

Species' population dynamics are tied to neonatal survival. White-tailed deer (Odocoileus virginianus) fawn survival varies according to spatially explicit patterns of natural (e.g., starvation, predation) and human-caused mortalities (e.g., vehicle collision). Our objective was to compare fawn survival under different, though representative, ecological conditions in Wisconsin USA. We identified 2 ecologically distinct study areas: the northern forest (NF) and the eastern farmland (EF). Beginning in May (2011-2013), we fitted fawns in both areas with radio-collars and tracked their survival daily until 31 August of the capture year. We obtained daily weather data for each study area to model weather effects on survival. We captured 89 (NF), and 139 (EF) fawns, and observed 42 (NF) and 43 (EF) mortalities. Predation mortality was higher than other mortality causes in the NF, and mortality due to natural causes other than predation was higher for fawns in the EF. Female fawns had higher survival than males, and fawns in 2011 in the NF had lower survival than fawns in 2012 or 2013. During the first 40 days of life, occurrence of precipitation associated with a threefold increase in daily hazard of death in the EF, but effects of daily low temperatures were trivial. In the NF, precipitation had little effect, but a decrease in daily low temperature by 0.56 degrees C increased the daily hazard of mortality by 5%. Because risks facing fawns vary with ecological context, understanding specific factors that affect fawn survival is important for predicting local outcomes of white-tailed deer management. (C) 2017 The Wildlife Society.