Restrictions on roaming
Until the past century or so, the movement of wild animals was relatively unrestricted, and their travels contributed substantially to ecological processes. As humans have increasingly altered natural habitats, natural animal movements have been restricted. Tucker
et al.
examined GPS locations for more than 50 species. In general, animal movements were shorter in areas with high human impact, likely owing to changed behaviors and physical limitations. Besides affecting the species themselves, such changes could have wider effects by limiting the movement of nutrients and altering ecological interactions.
Science
, this issue p.
466
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.
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