Survival and Cause-Specific Mortality of Neonate Elk in a Unique Predator Environment in the Black Hills of South Dakota and Wyoming, USA

摘要

We conducted a 2 y study of survival and cause-specific mortality of elk (Cervus elaphus) calves to determine the current status of elk occupying the southwestern region of the Black Hills National Forest, South Dakota and eastern Wyoming. We captured and fit 71 calves <= 10 d of age with expandable radiocollars during summer 2012 (n = 37) and 2013 (n = 34). We used known-fate analysis in Program MARK. to estimate summer (15 May-25 Sep.) and annual (12 mo) survival for elk calves. The top model for summer survival was {S-1-2wk,S-3-20wk} indicating mortality during 1-2 wk of age and 3-20 wk of age best explained survival; overall probability of surviving 20 wk was 0.79 (95% CI = 0.68-0.88). For annual (12 mo) survival, model {S-birthweight} had the lowest AIC(c) value indicating birth weight of elk calves best explained survival as heavier born calves had a higher probability of survival. The overall probability a calf survived to 12 mo of age was 0.75 (95% CI = 0.61-0.84). Cougar (Puma concolor) predation accounted for 81% of mortalities; remaining mortalities were from starvation (6.3%, n = 1) and unknown causes (6.3%, n = 1). Our results document high survival for calves likely due to productive habitats, an ecosystem-specific predator guild, and high alternative prey.