Does Age Matter? Effects of Age on Hibernation Patterns in Edible Dormice (Glis glis)

Abstract

We investigated the impact of age on patterns of hibernation in the edible dormouse. Multi-model inference showed that changes in hibernation duration, measured in 34 dormice implanted with temperature loggers, were best explained by effects of age. On average, each year of life shortened the hibernation duration by 15.17 days. While we did not observe significant changes in the timing of hibernation onset, every additional year of life led to an earlier mean termination of hibernation by 11.33 days. Since age did not influence torpor bout duration, arousal frequency or the duration of inter-bout euthermia, we conclude that the observed effects are not caused by ageing processes (e.g. physiological incapability). We discuss the observed age effects in relation to the unique life-history pattern in this species. Dormice invest into reproduction only in years with mast seeding. Thus, it may take some years until conditions are suitable for reproduction. While long hibernation periods predictably increase survival, an early termination of hibernation may provide an advantage in the establishment of high quality territories, which in turn may increase fitness. With increasing age, dormice are likely to favour investment into reproduction instead of maximising survival probability.metabolized lessn-6 PUFA compared to other fatty acids; in contrast to younger, still immature individuals. Thus, high availability ofn-6 PUFA may not only lower energy expenditure during hibernation, but also improve reproductive success in the subsequent year