Eyes on Nature

102 White-striped Free-tailed Bats

26 Apr 2021

A maternity roost of the White-striped Free-tailed Bat (Austronomus australis) was discovered in 2005 at Sydney Olympic Park and has since been part of the ongoing research project conducted by Marg Turton and volunteers in association with Sydney Olympic Park Authority.

The maternity colony resides in the roof space of a building at the Park in close proximity to Newington Nature Reserve. This is the first record of this hollow-dependent species roosting in a built structure, and the only known maternity colony in Sydney! This species begins breeding in late August, gives birth to one young between mid-December and late January.

Like many species of microbat, very little is known of White-striped Free-tailed Bat behaviour and habitat needs. To assist with managing the roost, an annual field survey is conducted in April at the end of the maternity season, to avoid impacting on pregnant females and very young bats. Adult bats and independent young born that season are captured as they leave the roost and they are microchipped, or ‘tagged’. Once tagged, information on the individual’s movements in and out of the roost is recorded by a sensor. This provides the ability to track the population over time and evaluate conservation management strategies. For example, tagging allowed the Authority to know the number of tagged bats using the roost, that some males will visit the roost year after year except during the peak maternity season, that bats will leave their roost in response to light pollution, and that the oldest microchipped bat to date is at least 12 years old.

As of April 2021, 102 White-striped Free-tailed Bats have been tagged since the beginning of the project!

Five individuals were caught during this year’s field survey, including one immature female, three breeding females (lactating), and one adult male. Upon examination, it was determined that the male’s wing had undergone a past injury that had since healed. The wing was torn resulting in significant loss of wing membrane. The ability for this male to fly and hunt despite such a severe injury from the past speaks volumes to the strength of these little creatures (weighing equivalent to almost 3 tablespoons of sugar when mature).

Records such as this add to what we know about this mysterious species, lending greater understanding towards conservation and care of White-striped Free-tailed Bats. This is the only long-term monitoring project of this species; information collected over the past decade has shed light on roost fidelity, social structure and longevity of this microbat species, and there is potential for us to learn much more.

The ability of the White-striped Free-tailed Bat to adapt to habitat loss and use built structures has presented an amazing opportunity for us to peek inside the lives of a species that would not otherwise be possible. We hope to share more insights into the future.

A female White-striped Free-tailed Bat (Austronomus australis) from the maternity colony at Sydney Olympic Park. © Marg Turton

A mature male examined during the April 2021 field survey exhibits a healed wing from past loss of wing membrane.
© Marg Turton

The release of a tagged White-striped Free-tailed Bat near the maternity roost. © Leroy Gonsalves