Hot entrances and sexy exits: Different trade-offs drive hibernation entrance and exit, with general implications for a warming world

All organisms face trade-offs between maintenance, survival, and reproduction, yet only recently has hibernation been viewed as a life-history decision rather than dictated solely by physiology and resources. Integrating life-history theory into studies of hibernation phenology is essential for predicting responses to climate change. Using 17 years of data from an enclosure-bound population of edible dormice (Glis glis), we investigated how physiological, resource, and life-history constraints shape hibernation timing. Immergence (entrance) was most strongly driven by physiological and resource-related factors—ambient temperature, body mass, and diet quality—while emergence (exit) was driven by life-history factors, specifically sex and age. This is the first study to isolate an effect of climate-driven warming on hibernation phenology while simultaneously accounting for diet quality, body mass, age and sex. These findings reveal that distinct processes shape immergence and emergence, highlighting the complexity of climate change impacts on hibernation and the need for life-history integration.