Main functions of loud vocalization in populations of edible dormouse Glis glis

The study aimed to determine when, during summer activity, males and females of the edible dormouse most often used loud calls. On this basis, an attempt was made to determine the main purpose of the emission of these calls. It was assumed that 1) if males have the most of loud calls in July, their emissions may be related primarily to the mating behaviour (which takes place during this period), and if they have the most of loud calls in August, their emissions are most likely concerned defence of food resources, 2) in females, most of this vocalization would occur in August due to the need to defend their food resources and 3) in both sexes, more vocalization would occur in the year of good beech fruit crop (when the dormice would reproduce) than in the year of no crop (when the dormice would not reproduce). To check these assumptions, the number of loud calls and “performances” (series of loud calls) emitted by the animals from two wild populations tracked by telemetry was noted. The mean number of “performances” and loud calls in males and females was higher in August than in July (when beech fruits ripen), but significant differences were found only for “performances”. Both males and females had significantly more “performances” and loud calls in the mast/breeding year than in the non-mast/non-breeding year. It seems that males and females use loud calls mainly to defend important resources and are, therefore, most often heard during the mast year.