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 radiocollared 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 survivorship 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% Cl = 63.3–80.0%) in the agricultural landscape and 57.2% (95% Cl = 47.5–66.3%) in the forested landscape. Thirty‐four‐week survival was 52.9% (95% Cl = 42.7–62.8%) in the agricultural landscape and 37.9% (95% Cl = 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% Cl = 37.6–56.7%) of 106 mortalities through 34 weeks. We attributed 32.7% (95% Cl = 21.9–48.6%) and 36.7% (95% Cl = 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% Cl = 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.

Elk Calf Survival and Mortality Following Wolf Restoration to Yellowstone National Park

“…For summer calf encounter histories (n ¼ 116), we used 1-week intervals to record radiotagging, survival, mortality, and censor events. We left-justified calf histories, so survival estimates related to calf survival by weeks irrespective of the actual date calves were radiotagged (Vreeland et al 2004, Raithel 2005. We first modeled constant summer survival through 20 weeks.…”

Can Coyotes Affect Deer Populations in Southeastern North America?

“…Ample evidence exists in the literature demonstrating that coyote predation on white-tailed deer (Odocoileus virginianus), particularly neonatal fawns, can be high (e.g., Cook et al 1971, Bartush and Lewis 1981, Whittaker and Lindzey 1999, Vreeland et al 2004. After reviewing this literature, Ballard et al (2001) concluded that coyotes can be a significant mortality factor for deer, and Ballard et al (1999) suggested that coyotes have replaced wolves in their role as deer predators in parts of northeastern North America, frequently taking adults during winter as well as neonatal fawns.…”

Increased overwinter mortalities of white-tailed deer (Odocoileus virginianus) fawns during a drought year

“…Studies that have continued to monitor radiomarked fawns past the first 8 weeks of life have attributed older fawn mortalities to hunting, poaching, and vehicle collisions (Vreeland et al 2004; Rohm et al 2006;Burroughs et al 2006;Hiller et al 2007). Thus, another method for estimating deer vital rates is by analyzing deer harvest data (e.g., fawn-to-doe kill ratios, age structure of harvest).…”