Roost selection by Bats in woodchipped forests
This research is part of a broader study of the long-term impact of woodchip logging. It focused on species dependent on old-growth elements in the forest - tree cavity-dwelling bats. The aim was to determine the roosts selected by Gould’s Long-eared Bat and the Little Forest Bat in forests that had been logged for woodchips 25 years earlier. The bats were caught in harp traps, radio-tracked to roost trees and a comparison was made between trees used and trees available. Both bat species were selective in the species, size and condition (live/dead) of their roost trees, and in landscape characteristics, such as logging history, topography and aspect. Roost preferences varied between and within the species. Gould’s Long-eared Bat selected, as maternity roosts, cavities in large (dbh: mean 73.6 cm), live trees, located in coupes in unwoodchipped forest on slopes with eastern or southern aspects. Adult males showed a preference for roosting under exfoliating bark of dead wattle. Both male and female Little Forest Bats selected cavities in large (dbh: mean 68.7 cm) trees. Their roosts were preferentially located on south and east facing gullies and mid-slopes. Neither species used live trees <50 cm dbh, although they dominated the forest. Microchiroptera is a poorly studied taxon and we are far from able to adequately define the habitat requirements of many species. While roost preferences are complex, there is a consistent pattern of dependence on cavities found in dead or decaying trees. This and earlier studies offer no evidence that regrowth vegetation in intensively managed forests provides roosting habitat for tree-roosting bats. Rather, conservation of these species depends on preservation and recruitment of old growth elements of forests.