Effects of climate change on life-history traits in hibernating mammals

1. Animals can respond to climate change through changes in behaviour, morphology or life-history traits. Changes in life-history traits do not occur independently, as they trade off or co-evolve with other traits. 2. Hibernation is a life-history trait used to cope with periods of low resource availability. The energetic and survival benefits of hibernation depend on environmental conditions. Climate change-induced changes in hibernation patterns are therefore likely to affect other life-history traits through trade-offs. 3. We systematically reviewed the literature to: 1) identify studies testing for associations between climatic variables and life-history traits in mammalian hibernators; and 2) assess variation in responses between species. 4. Air temperature was the most commonly measured climatic variable, and phenology of hibernation emergence was the most commonly studied life-history trait. In most studies and species, emergence date became earlier, litter size increased and the number of interbout arousals increased with increasing air temperature. 5. Despite being considered key life-history traits due to their potential to influence population dynamics, our search returned no studies on the effects of climatic variables on the age of primiparity or on the age distribution of reproduction. 6. Directions of associations between climatic variables and life-history traits often differed between species, and both species- and sex-specific variations occurred in response to climatic variables for some traits. 7. We highlight the importance of long-term, species-specific research, and the need for further studies on indirect effects of climatic cues on co-adapted traits to understand the potential for mammalian hibernators to respond to ongoing and future climate change