THE Goulburn Broken Catchment Management Authority (GBCMA) is highlighting the importance of tree hollows for wildlife in its 2025 Year of the Tree Hollow community awareness campaign.

Three local species of owl that depend on knot holes and other branch cavities to survive are the powerful owl, Australian boobook, and Australian owlet-nightjar.

GBCMA project officer Janice Mentiplay-Smith said the powerful owl (Ninox strenua) was Australia’s largest owl.

“In the Goulburn Broken catchment this magnificent top order predator lives in large tracts of forest where it can access territory, nesting hollows, and food,” Ms Mentiplay-Smith said.

“A menu favourite is the brushtail possum, which also relies on tree hollows.”

Powerful owls have a slow, double-note ‘whoo-hoo’ call that can be heard across one or more kilometres, and habitat and tree hollow loss is one of the challenges the powerful owl is facing.

The Australian boobook (Ninox boobook) is the smallest of Australia’s 11 owl species.

Its eyes are fixed within bony structures called ‘sclerotic rings’ meaning it cannot move its eyes within the sockets so it can remain perfectly still and turn its head up to 270 degrees in either direction.

Its forward-facing eyes allow for greater depth perception to help it calculate the distance to its next meal.“Like all owls, the Australian boobook has excellent night-time vision, however, possibly as an evolutionary trade off, it does not perceive colour very well,” Ms Mentiplay-Smith said.

Ms Mentiplay-Smith said, that with classic “angry bird” eyes,

The Australian owlet-nightjar (Aegotheles cristatus) is one of the Goulburn Broken catchment’s most interesting smaller nocturnal birds and is the only species of owlet-nightjar in Australia.

The species is insectivorous and hunts at night to dine on a variety of small invertebrates such as moths and spiders and catches its food ‘on the wing’ as well as from the ground.

It is dependent on tree hollows and branch cavities to nest and safely roost in during the day.

The Year of the Tree Hollow is supported by the Victorian Government through the Our Catchments Our Communities stewardship program.

For more information, visit http://birdlife.org.au/projects/powerful-owl-project