An Ecological Study of Sminthopsis crassicaudata (Marsupialia : Dasyuridae) II.* Behaviour and Social Organization

Abstract

The behaviour of Sminthopsis crassicaudata was studied by mark-recapture techniques at Werribee, Vic., from 1972 to 1976. Observations of nocturnal behaviour were also made at Fowlers Gap Station, N.S.W. S. crassicaudata usually nest solitarily in the breeding period (August–March), but up to 70% of individuals share nests in groups of from two to eight during the non-breeding period (April–July). These nest-sharing groups are impermanent and appear to be random aggregations of individuals. Most nest-sharing in the breeding period involves pairs of a male with an oestrous female. Both males and females inhabit large overlapping ranges in the breeding and non-breeding periods. Males seem to move their nest sites more frequently than females; this supposition is supported by observations of nocturnal behaviour. The ranges of individuals are unstable in space and are best described as 'drifting home ranges'. The only animals that may become territorial are breeding females, and these probably defend only a small area around the nest. Males do not appear to defend their range at any time. The adaptive significance of the social system is discussed.