Habitat Ecology Information

Whats Lurking In Your Back Yard? – #1 The Powerful Owl

This series looks at the variety of fauna that may be found in the suburban backyard or local reserve and the diversity may be surprising to some people. The obvious fauna are the vast array of birds that are readily seen by day and some by night, but there are numerous species that are nocturnal. Some of these nocturnal species people are familiar with as they tramp across the roof at night with what sounds like hobnail boots on, or they hear fighting in the backyard over food and territory. Others are cryptic and may only be seen infrequently when they enter the house for warmth and shelter. Each week I will highlight a different species that may be found in and around Melbourne’s backyards, parks and reserves, some may be familiar others less so.

#1 Powerful Owl
(Ninox strenua)

The Powerful Owl is Australia’s largest owl and can be found in a variety of habitats including open forests and woodlands and along sheltered gullies and waterways. It is also known to frequent farmlands and suburban parks and gardens. The City of Melbourne has a number of individuals that are known to frequent the parks and gardens of the city. The Powerful Owl can be found along the east coast of Australia from Queensland to Victoria and within Victoria it has been listed as a Vulnerable species under the Flora and Fauna Guarantee Act 1998.

The Powerful Owl is a nocturnal species, hunting at night feeding on possums and gliders, rabbits and small birds. It is not uncommon to see a roosting owl with its nightly catch firmly held in its talons. It is a secretive species and blends well into the trees that it roosts in, often lower down in branches protected by the closed canopy of the tree it has chosen to roost in. Often the only sign that an owl is or has been there are the casts of regurgitated fur and bone on the ground, the remains of its nightly feast.

The home range of a Powerful Owl will depend on the available food source but it is estimated to be around 1250 hectares per owl. That’s about 2km radii. The owls can live for 30 years and they mate for life. They usually raise one chick per season with breeding starting around May. The male prepares the nest in a large tree hollow and the female will incubate and brood the chicks before emerging later to assist in the obtaining the food requirements for the chick. However it is not uncommon for the owls to have two chicks, although this may be dependent on seasonal food availability.

The biggest threat to Powerful Owls is the loss of suitable large trees with large nesting hollows. Hollows need to be at least 0.5 metres across and 1.0 metres deep. Changes to canopy structure that result from fire, habitat fragmentation and clearing also pose a threat due to possible reduced food availability as possums become less frequent.

The Powerful Owls call is a deep, double hoot: ‘woo-hoo’

© Habitat Ecology 2012