LONG LIVING AND REPRODUCTION SKIPPING IN THE FAT DORMOUSE

Abstract

We studied the reproductive strategy of a population of fat dormice (Myoxus glis) breeding in nest boxes in a beech forest on the southern Alps, Italy. In eight years of data collection (1991-1998), we observed births only in 1991, 1992, and 1995. We did not observe young during the autumn dispersal in the remaining five years. Reproduction was not correlated with high rainfall, low temperature in summer, or with population density. Reproduction was only observed in years of beech mast seeding. Body condition of adults when they emerged from hibernation did not differ between years with and without repro- duction, suggesting that the adults may avoid breeding when the young have a low prob- ability of surviving their first winter. A capture-recapture analysis on individually marked adult fat dormice identified a very high yearly survival rate (0.86-0.92), close to that of large herbivorous mammals and much higher than that typical of other rodent species with similar body size. No influence of sex on survival or recapture probability was detected. The long life span expectancy of an adult dormouse (averaging nine years) is the prerequisite for the infrequent breeding strategy adopted by this rodent species to cope with an unpre- dictable food source. A high survival rate despite the small body size may have been possible because of the long hibernation time ( .6 months). Long life span and intermittent breeding make the life history of fat dormice unique among rodents.