Is energy supply the trigger for reproductive activity in male edible dormice (Glis glis)?

In edible dormice (Glis glis) reproduction is synchronised with the intermittent masting of the European beech (Fagus sylvatica). In years of mast failure dormouse males seem to anticipate future low food availability and fail to develop functional testes. We hypothesised that the availability of high-quality food is linked to male reproductive capacity, because of high male energetic demands during gonad maturation. We therefore evaluated the relationship between beech seed production and male reproductivity in the field between 1993 and 2005. In order to know whether the energy content of the food as such triggers sexual capacity, we supplemented high-quality food in the field for 3 years and investigated reproductive output, reproductive capacity, and body mass changes. Results revealed that male reproductive capacity was positively linked with beech seed production. Body mass changes of reference males during the high reproductive year further revealed high energetic demands of male reproduction, which were counter balanced in food-supplemented males. However, in contrast to our assumptions, artificial food supply during a year of mast failure failed to evoke high reproductivity in edible dormice. The availability of high-quality food can therefore be ruled out from being the primary trigger for sexual activity in male edible dormice.