No abstract

No abstract

Annual variation in commencement of hibernation was observed for each sex-age class of the Siberian chipmunk (Tamias sibiricus) in an oak forest in northern Japan for 7 years (1973)(1974)(1975)(1976)(1977)(1978)(1979). Neither air temperature, the duration of preparatory periods for hibernation, nor body mass were directly related to the annual variation. Hibernation began remarkably early in 1974 and 1975. These years were characterized by a population of chipmunks at high density and a failed crop of acorns. Competition for nest sites and low availability of food may be factors encouraging early hibernation. Adult females entered hibernation first, followed by adult males, juvenile females, then juvenile males. Adult males entered hibernation after 99.1 % of females in their ranges had selected hibernation burrows. Males may need to confirm the location of the females' burrows, and this could lead to greater mating success in spring, as chipmunks change hibernation sites yearly. Juveniles entered hibernation later than adults, perhaps because it was difficult for them to select burrows while adults were still active.

ABSTRACT. Field observations on 117 tree shrews (Tupaia glis) were conducted over a period of six months in Singapore. Of 19 groups (pairs or harems, with or without offspring), nine changed their composition mainly through the disappearance of juveniles. Juvenile males tended to disappear earlier than juvenile females. The areas used by the groups remained stable throughout their disappearance and membership changes. The onset of mating was observed in December, and the synchronous disappearance of offspring of the preceding reproduction typically occurred in late January. However, in one group, two litters coexisted. Offspring were usually excluded from their group presumably by the adult member of the same sex. Males disappeared at the timing of oestrus in their mothers, while females probably disappeared during the later stages of pregnancy of their mothers.

No abstract