Survival rates, mortality causes, and habitats of Pennsylvania white-tailed deer fawns

Abstract

Estimates of survival and cause-specific mortality of white-tailed deer (Odocoileus virginianus) fawns are important to population management. We quantified cause-specific mortality, survival rates, and habitat characteristics related to fawn survival in a forested landscape and an agricultural landscape in central Pennsylvania. We captured and radiocol-lared neonatal (<3 weeks) fawns in 2000–2001 and monitored fawns from capture until death, transmitter failure or collar release, or the end of the study. We estimated survivor-ship functions and assessed influence on fawn survival of road density, habitat edge density, habitat patch diversity, and proportion of herbaceous habitat. We captured 110 fawns in the agricultural landscape and 108 fawns in the forested landscape. At 9 weeks after capture, fawn survival was 72.4% (95% CI=63.3–80.0%) in the agricultural landscape and 57.2% (95% CI=47.5–66.3%) in the forested landscape. Thirty-four-week survival was 52.9% (95% CI = 42.7–62.8%) in the agricultural landscape and 37.9% (95% CI = 27.7–49.3%) in the forested landscape. We detected no relationship between fawn survival and road density, percent herbaceous cover, habitat edge density, or habitat patch diversity (all P>0.05). Predation accounted for 46.2% (95% CI=37.6–56.7%) of 106 mortalities through 34 weeks. We attributed 32.7% (95% CI=21.9–48.6%) and 36.7% (95% CI=25.5–52.9%) of 49 predation events to black bears (Ursus americanus) and coyotes (Canis latrans), respectively. Natural causes, excluding predation, accounted for 27.4% (95% CI=20.1–37.3) of mortalities. Fawn survival in Pennsylvania was comparable to reported survival in forested and agricultural regions in northern portions of the white-tailed deer range. We have no evidence to suggest that the fawn survival rates we observed were preventing population growth. Because white-tailed deer are habitat generalists, home-range-scale habitat characteristics may be unrelated to fawn survival; therefore, future studies should consider landscape-related characteristics on fawn survival.