Sex-specific behaviors of hunted mule deer during rifle season

Abstract

Animal populations face increased threats to mobility and access to critical habitat from a variety of human disturbances including roads, residential development, agriculture, and energy development. Disturbance from human hunting is known to alter habitat use in ungulates, but recent work suggests that hunting may also trigger the onset of migration. Whether this holds true across ungulate species and hunting systems warrants further empirical testing. We used global positioning system location data from mule deer ( Odocoileus hemionus ) in south-central Wyoming, USA, to evaluate the sex-specific effects of hunting on habitat selection and migratory behavior from 2016 to 2018. We modeled habitat selection before and during hunting season using a step selection function, and we used time-to-event models to evaluate if hunting triggered migration. We found habitat selection and migration timing to be sex specific. Males responded to hunting season by selecting security habitat away from motorized routes, whereas females used habitat through hunting season that retained higher forage quality. Weather, as indexed by temperature and precipitation (i.e., snowfall), influenced migration timing for males and females. Migration timing in males was influenced by migration distance, where individuals traveling >50 km tended to migrate earlier than individuals moving <50 km. For deer that survived to rifle season, hunting was less influential on migration timing than environmental factors. Rifle season increased the likelihood of migration by 2% in females and <0.01% in males compared to outside rifle season. Our findings suggest that roadless areas on mule deer summer ranges and within migration corridors reduce the effects of hunting disturbance. Consequently, managers may consider limiting the use of motorized vehicles as a method for reducing effects on migration from hunting disturbance.