Exploring context-dependent variation in brown bear denning behavior

Mammals use denning to reduce their metabolic activity to survive periods of low food abundance and prolonged adverse weather. We used very high frequency and global positioning system collar data and located 478 winter den sites of brown bears ( Ursus arctos middendorffi ) on the Kodiak Archipelago, Alaska, USA during 1982–2021 to evaluate three nonexclusive hypotheses regarding den site selection and timing of den entry and exit. Based on the physiography hypothesis, we predicted that adult females (solitary or with dependent young) and subadults (male and female) would den at higher elevations or on steeper slopes than adult males to reduce the risk of intraspecific killing, including infanticide. Following the young protection hypothesis, we predicted that to increase cub survival, adult females with dependent young would segregate temporally from adult males, solitary adult females, and subadults by arriving at dens earlier and leaving dens later. Finally, based on the food quality dependent hypothesis, we expected less distance (km) between adult male den site locations and the nearest North Pacific salmon ( Oncorhynchus spp.) spawning stream compared to that of adult females and subadults, due to feeding site (i.e., higher-quality food resources) exploitation by adult males. None of our predictions were supported as we found no differences in den site selection or timing of den entry and exit among sex and age classes of Kodiak brown bears. Whereas these patterns might reflect brown bear behavioral plasticity, we recommend future research to further test for behavioral plasticity in denning of brown bears.