Annual and seasonal variation of survival rates in the garden dormouse (Eliomys quercinus)

Abstract

Annual local survival of the garden dormouse Elyomis quercinus, a small, hibernating rodent, was studied by Cormack–Jolly–Seber models. The survival rates differed significantly between the 4 years of the study; the average rate was 0.38 (95% confidence interval: 0.25–0.52). Survival rates were not significantly different between sexes. Because all garden dormice were captured after weaning, pre-weaning survival could not be estimated. After weaning, the annual survival rates did not differ between age cohorts. In order to find out which phases within the annual cycle were more prone to mortality, survival was studied on a bimonthly scale as well. Survival during hibernation was estimated to be close to unity, while survival during the active phase of life in summer was considerably lower. The winter temperatures of the study years were similar to the long-year average; thus garden dormice were well adapted to these average conditions. Although hibernation is energetically challenging, it is not necessarily accompanied by increased mortality, as found in other studies focusing on survival during hibernation.