9th International Deer Biology Congress

AUTHORS: Cody A. Schroeder and Kelley M. Stewart – University of Nevada Reno, Program in Ecology, Evolution, and Conservation Biology

ABSTRACT: Migration is an important adaptation for species inhabiting variable ecosystems. Many ungulate populations make seasonal migrations between summer and winter ranges; however, peer-reviewed literature indicates migration routes and distances traveled can be highly variable. Few studies have quantified these migration strategies in the context of true measures of fitness such as body condition or population-level effects on survival. We used data from over 750 radio-collared mule deer (Odocoileus hemionus) to test hypotheses relating survival to body condition, sex, environmental conditions, and migratory strategy. Adult survival was most parsimoniously explained by models containing co-variates for sex, season, body condition and migration distance. Over-winter survival of juvenile mule deer was best explained by models containing co-variates for sex, body mass, and a winter severity index. Adult and juvenile survival was lower for males than for females, even after accounting for mortality caused by human harvest. These results suggest population models may overestimate male survival outside of harvest reporting. We also provide preliminary results that suggest adult survival varies with respect to migratory behavior and body condition, which may have direct management implications for decisions affecting harvest quotas, habitat improvements, and energy development policies.