They like it cold, but only in winter: climate‐mediated effects on a hibernator

Variations in ambient temperature (Ta) profoundly influence energy consumption in endotherms and therefore their survival and fitness. But depending on whether endotherms are hibernating or active, the same changes in Ta may have opposing consequences for their energy consumption.
The aim of this study was therefore to investigate how variations in Ta, occurring during hibernation and during the active period of a hibernator, affect different fitness relevant traits.
To understand whether changes in Ta impact phenology, body mass and reproduction in a small mammalian hibernator, we analysed Ta variations and detailed capture-mark-recapture data on edible dormice (Glis glis) collected between 1993 and 2016 in South-West Germany.
Results revealed that during hibernation a Ta increase of 1°C advanced the date of first capture after hibernation by 6 days, but only if food availability during the preceding year was low. In contrast, after years of comparatively high food availabilit...