COMMUNAL NESTING BETWEEN BREEDING FEMALES IN A FREE-LIVING POPULATION OF FAT DORMOUSE (GLIS-GLIS L)

The breeding biology of a free living population of fat dormouse (Glis glis) was studied for three years (1982-1984) in a deciduous forest on Colli Berici (Vicenza, Italy), where 57 nest boxes were set, to assess whether communal nesting and communal nursing occurred. Nest box occupation was monitored and animals were individually tagged. Copulation occurred mostly in the first part of July; births in the first part of August. By counting the number of suckling young, the average litter size was found to be 4.7 (range = 2-7). Only one litter per season was produced. Females matured after their first hibernation, or, at latest, after the second one. The growth rate of young from small litters was significantly greater than that of young from large litters. Of the nests found in the nest boxes, 27.5% were communal nests with two (in one case three) breeding females and their litters. Therefore, about 44% of the females nested in communal nests. Whenever a difference in age allowed litters to be told apart, females in communal nests were observed to nurse each other's pups. Communal nesting was not correlated with the availability of nest boxes or natural holes, and the number of communal nests was significantly higher than expected by chance. The only case of proved relatedness between conesting females, was one of mother and daughter.