Gender differences in activity patterns of American mink Neovison vison in Germany

摘要

Circannual and circadian activity patterns of American mink Neovison vison were studied in a fishpond area in northern Germany. Fourteen mink were radio-tracked, nine of them (five males, four females) for at least 6 months, some of them even up to 21months. Both sexes have reduced activity rates in winter months and showed a considerable increase of activity during mating season (March). In summer months--during the pup raising period--female activity continued to be high. Male mink, on the other hand, were less active with the exception of August and September. During this time, dispersal of juveniles takes place with resident males increasingly having to defend their territories. Circadian activity rhythms differed markedly between sexes. All investigated females exhibited ;a perennial diurnal pattern. Female activity during twilight and night was significantly lower than during daylight. Three investigated male mink showed a typical nocturnal course throughout the year. Daylight activity of these animals was very low, increased during dusk and dawn activity rates and stayed at a higher level during the night. Two males behaved arrhythmic; they did not prefer any time of the day for activity. The observed temporal strategies were discussed incontext of intra-sexual territo-riality, sexual dimorphism in body size and different environmental factors.