Differential habitat use by a local population of the velvet-furred rat, Rattus lutreolus velutinus (Thomas 1882), in wet sclerophyll forest, SE Tasmania

This study investigates a reported decline in the proportion of male Rattus lutreolus velutinus in a trappable population during winter. A four hectare trapping grid was maintained between March 1989 and June 1990 in wet sclerophyll forest which had been burned by wildfire in 1967. The forest community displayed both structural and floristic heterogeneity. Four habitat groups were defined and capture data from 17 four-weekly trapping sessions are compared within these groups. R. l. velutinus exhibit a clear preference for areas of densest cover to one metre height and an avoidance of areas with little or no ground cover. During winter, areas of densest cover are utilized almost exclusively by females; males occupy areas with less cover at lower densities. During the breeding season, females continue to be captured in areas of densest ground cover. These areas are visited by numerous males in reproductive condition. An ecophysiological assessment of individuals in the trappable population was undertaken using routine blood sampling and the influence of environmental and artificial stressors on some haematological and endocrinological parameters is examined. Significant differences are evident between sexes for some measured parameters but no important differences are evident between the physiological states of individuals captured in different habitat groups. The results of this study indicate that a local population of R. l. velutinus may use habitat differentially but that individuals captured in different habitat groups do not differ in their physiological profiles or their ability to cope with environmental stressors. The intersexual difference in habitat use is discussed in relation to social spacing, resource utilization and female choice.