The Powerful Owl is Australia's largest owl (about 60cm tall) and hunts possums and gliders. They are relatively rare and are classed as a Vulnerable species on the Victorian Flora and Fauna Guarantee Act 1988 Threatened List. In 2023 the Warringal Conservation Society received a Banyule City Council Environmental grant to use new audio monitoring techniques to detect Powerful Owls.
In Banyule, we are lucky to have Powerful Owls living in habitat along the Yarra River corridor. For such large birds, Powerful Owls are not easy to detect. They have large territories and are very good at hiding during the day. They are most active at night when it is hard to see them. This makes it difficult to tell how our local Powerful Owls use habitat and whether they are thriving.
The Powerful Owl has a distinctive double hoot call that gives away its presence. However, their territories span many kilometers and nocturnal outings to listen for calls are often unsuccesful. Wildlife audio monitoring technology has become much more accessible recently. With assistance from the Banyule Council, Warringal Conservation Society purchased miniature programmable audio recorders and deployed these at strategic locations to pick up owl calls. Recordings were analysed as a spectrogram (plot of frequency versus time) and low frequency double hoot calls were readily detected. From February to October 2023, Powerful Owl calls were detected on over 250 occasions at 13 sites from Yarra Flats to Westerfolds Park. Changes in the use of habitat were evident over the year and may be related to the winter breeding season. Call detection and observations on the ground suggest that there are three or four Powerful Owls in the area surveyed. All data collected is reported to Banyule Council to inform management of our wonderful bushland habitat.
We are pleased with how successful this project has been and grateful to the Banyule Council for the support they have provided,