Long-Term observations of a White-Striped Free-Tailed Bat <i>Austronomus australis</i> roost in a building in Sydney

ABSTRACT This paper assembles observations to date from an ongoing, long-term study that has focussed on a maternity colony of the White-striped Free-tailed Bat Austronomus australis located in the only recorded roost in a building (Turton and Hoye 2011). As of Winter 2024, this study has monitored the roost for 16 years making this the longest continuous bat PIT tag study carried out in Australia to date. As a difficult to study species, the location of this roost provided an excellent opportunity to study this cryptic bat. The roost is used year-round, with the population of the roost varying seasonally, the same bats returning year after year showing strong roost fidelity to the building and surrounding natal area. The role of males is discussed and the first potential observation of harem structure in this species noted. Radio-tracking has shown roost switching behaviour between the building and nearby roost trees occurring, with the colony appearing to conform to a ‘fission-fusion’ roosting pattern. The longevity of the tagged bats was recorded with several bats reaching in excess of 10 years, and one male reaching at least 14 years of age (age unsure at time of tagging).