Use of Roost Sites by Four Species of Bats in State Forest in South-Eastern Tasmania.

Abstract

Roosting requirements and movements between foraging areas and roost sites were studied in Eptesicus regulus, E. sagittula, Chalinolobus morio and Nyctophilus geoffroyi in an area of artificially regenerated eucalypt (Eucalyptus) forest surrounded by mature eucalypt forest. Movements between traps and roost sites were normally about 1 km, with the maximum distance recorded being 4.8 km for a female N. geoffroyi. Different species of eucalypts were used as roost sites in proportion to their occurrence in the forest. However, large trees over 80 cm d.b.h. were favoured. There was no tendency to avoid roost sites close to the ground. Spaces used as roost sites had one dimension little greater than the bat itself. Five types of roost sites were distinguished: in fissures, inside burnt-out boles, in hollows, under bark and on the ground. Individuals changed roost sites frequently but roosts used by any one individual were in the same general vicinity. The factors associated with production of roost sites in trees were: large size, overmaturity, death, rot and fire. No bats were found to roost in regenerated forest. Patches of mature forest will need to be retained to ensure a shortage of roosts does not occur as more areas of mature forest are converted to production forest.