ABSTRACT

More than 5000 Muscardinus avellanarius were weighed during investigations carried out in Lithuania in 1981-1999. Weights of dormice changed continually during the year. The steadiest average weight of adult males was in May - July (between 17.0 g to 17.9 g), before hibernation it increased to 29.8 g. Weight dynamics of females had some different features connected with reproduction. The weight of juveniles depended on the time of their birth. The maximum weight registered in Lithuania before hibernation was: in adult males - 42.8 g, in adult females - 35.0 g, in juveniles - 33.5 g. During hibernation M. avellanarius lost on average 33% of their maximum autumnal weight. In autumn before hibernation M. avellanarius weights may be higher in populations in the north of its range than in populations in the south. The use of weight to determine the age of M. avellanarius is very limited because the weights of separate age groups overlap in many cases.