Life under a sandstone overhang: The ecology of the eastern cave bat Vespadelus troughtoni in northern New South Wales

Abstract

We studied the eastern cave bat (Vespadelus troughtoni) in northern New South Wales to provide ecological information on roosts and foraging. Radio-tracking of five bats was supplemented with opportunistic visits to roosts over five years. One male was radio-tracked and its roost was within a corrugated iron roof cavity of a dairy. Maternity roosts were located in the overhangs of large sandstone caves usually containing a dome at the rear. Searches of nearby cliff-lines found that small caves, crevices and overhangs were not used as day-roosts. Nor did any radio-tagged bat roost in tree hollows. Colony size of one tight roosting cluster was estimated as 240 individuals. Radio-tagged bats frequently switched roosts, while opportunistic visits over a five-year period often found caves unoccupied. Most movements between roosts were within 1.5 km, although one female moved about 3.75 km between roosts. One radiotagged female shifted roost to beneath the corrugated iron of a farm-shed that supported at least 50 bats, predominantly females with young. Observations of foraging radio-tagged and lighttagged bats were frequent along a stream lined with trees, but surrounded by cleared paddocks. Foraging was observed in the air space above the creek, interspersed with occasional rapid flights across paddocks (> 500 m). We suggest that a key requirement for V. troughtoni in the rural landscape is the presence of native vegetation in close proximity to roosts, although extensive forested areas may not be required. Education of local communities about the sensitivity of these bats at cave roosts would be an important contribution to their conservation.