Article by Clancy Hall, conservation biologist
Have you ever heard a microbat in the night sky?
The most easily heard local microbat call is that of the white-striped free-tailed bat. The frequency of their vocalisations are the lowest of any Australian bat, and well within the auditory range of most people. Head outside after dusk and listen for a regular metallic ting…ting…ting…
Named for the two bright white stripes at the junction of its belly and wings, the white-striped free-tailed bat (Austronomus australis) is the largest hollow roosting bat species in Australia. It is found in a diverse range of habitats, with the exception of those in the top end. A common characteristic across its range, however, is its preference for roosting in very old eucalypts, especially forest red gums (E. tereticornis) and grey gums (E. propinqua). Large colonies of up to 300 individuals have been recorded roosting down into the trunks of trees, many hundreds of years old. We know from the radio-tracking of individuals, that these large colonies may act as a hub for a larger network of roosts in the area, with bats regularly returning home to their extended family after spending time alone or in smaller groups of approximately 20 individuals.
Unlike some microbats, white-striped free-tailed bats do not enter a torpor or hibernation during winter but take seasonal migrations north. These warmer temperatures afford them a comparative smorgasbord of insects that is otherwise unattended by many of the smaller microbat species who opt to simply shut down over the winter months. Menu items consist mainly of moths, as well as grasshoppers and beetles, some as large as Christmas beetles!
You can help white-striped free-tailed bats by preserving old eucalyptus trees, limiting the clearing of forested areas and being fire-smart.