The ecology of bats in south-east Australian forests and potential impacts of forestry practices: a review

Abstract

Bats are important contributors to Australia's mammal diversity and are ecologically diverse, feeding on insects, fish, small vertebrates, nectar, pollen and fruit. As such they are likely to play key ecological roles as regulators of invertebrate populations and pollinators of forests. Although somewhat contradictory, current evidence suggest that logging impacts on the species richness and activity of insectivorous bats when forest structural complexity and the number of available roosting hollows are reduced. Inconsistent results concerning impact on species richness stem from methodological problems with bat surveys. "Rare" species are often recorded in low numbers, preventing habitat preferences and disturbance impacts from being determined. Radio-telemetry has demonstrated that roosts in hollows of mature trees are a critical resource for many species of bats due to species specific requirements. However, it is not yet possible to state whether bat populations are directly limited by the availability of hollows in areas where a mosaic of logged and unlogged forest exists. Although data on foraging areas are extremely limited, some species appear to be flexible, capable of flying across open areas and exploiting those rich in invertebrates. Some species (e.g., Vespadelus) show a high degree of site attachment, possibly indicating a susceptibility to logging, however, the extent of site fidelity for most species is unknown. As pollinators, megachiropteran bats are likely to play a key role in maintaining the genetic diversity currently present in eucalypts by facilitating long-distance movement of pollen. Areas that are productive in nectar and pollen have a high conservation value for these bats and many other nectarivores, however, the age at which important nectar-producing trees flower is generally not known. The extent to which wildlife prescriptions, such as habitat trees and mosaics of small reserves, mitigate these impacts on bat species requires urgent research.