Are Hibernators Toast? Global Climate Change and Prolonged Seasonal Hibernation

This review examines the multifaceted implications of global climate change on mammalian hibernators, emphasizing physiological, ecological and phenological impacts. While high-latitude habitats are experiencing faster overall warming, tropical and southern hemisphere regions face more unpredictable and variable climate alterations. Increasing temperature can directly affect hibernators by elevating hibernacula temperatures, shortening torpor bouts, increasing arousal frequency, and depleting energy reserves crucial for survival and reproductive success. Conversely, cold anomalies due to climate change may cause disruptive late-season cold snaps, affecting post-hibernation recovery and reproduction. The phenological timing of hibernation, emergence and reproduction is becoming increasingly decoupled from environmental cues, creating potential mismatches that threaten fitness and survival. Habitat modifications, including urbanisation, further modify microclimates, introducing new risks and opportunities influencing hibernation behaviour, resource availability and susceptibility to disturbances and diseases. Despite anticipated physiological resilience owing to broad thermal tolerances, many hibernating species already inhabit extreme environments and operate near their physiological limits, thus are even more at risk through ecological disruptions as climate variability intensifies. Ultimately, the capacity for adaptive phenotypic plasticity combined with ecological resilience will determine species' future persistence, with high-latitude species potentially more vulnerable to ecological disruptions like habitat loss, predation and disrupted food webs, while tropical species face greater physiological risk.