August's bird of the month: Powerful Owl

5 things about Powerful Owls

5 things you may or not know about your August bird of the month, the Powerful Owl

1. They’re Australia’s largest owl species

Powerful by name, powerful by nature – the Powerful Owl is the largest of Australia’s 11 resident owl species. Adult birds can reach 60cm in length, weigh up to 1.45kg and have a wingspan of up to 1.4 metres across, and their huge talons are almost the size of a human fist. Their distinctive hulking silhouette is also characterised by a relatively small rounded head, long tail and big yellow feet and eyes.

Since they’re nocturnal, you’re most likely to spot a Powerful Owl during the day, roosting in the shade of a dense tree either alone, in pairs or in family groups of three or four. If their presence isn’t revealed by other birds harassing them, whitewash and pellets are tell-tale signs of a Powerful Owl roosting nearby.

Remember: Powerful Owls are sensitive to human disturbance. Never get too close to a roosting owl or stand directly underneath one, especially during the breeding season.

2. They (make) a real hoot!

Powerful Owls are also one of the only Australian owls that make the classic owl call – a deep, resonant double-barrelled whoo-hoo that can be heard from several kilometres away. This call is most commonly heard during the winter months, when breeding occurs and pairs are establishing their territories.

Once associated with the deep, damp forests of Australia’s eastern and south-eastern seaboard, this sound is a more familiar occurrence in suburban areas, especially in remnant bushland along waterways where hollow-bearing trees are more likely.

“Powerful Owl (Ninox strenua)” from xeno-canto by Eddy Smith

Their other calls include a shrill piping, a thin trill and a low, sheep-like bleating or growling call.

3. They’re apex predators

With their mighty talons, exceptional binocular vision and silent wings, Powerful Owls reign supreme over parks, open forests and gardens.

Powerful Owls hunt at night and during dusk and dawn on moonless nights. They’re specialised in taking medium to large tree-dwelling mammals (especially possums and gliders), swooping down and plucking them from the side of a tree with their powerful talons. Often, adults will clutch the remains of their prey while roosting.

They’re also known to prey on flying foxes, roosting birds and large insects – and are said to be the only bird in Australia that carries more than its own body weight in food in flight.

Powerful Owls swallow much of their prey, including fur, feathers and bones. Later, they regurgitate the undigestible parts of their food in the form of a grey, thumb-sized pellet, which provides valuable information about their diet.

4. They mate for life

Powerful Owls are lifelong monogamists, forming pairs that are known to last over 30 years.

Pairs establish permanent territories that they defend year-round, while their breeding cycle spans 10–11 (or even more) months of the year.
Males prepare the nest in a large vertical tree hollow, and hunt and provide food for the female and young during the first half of the nesting period. Both birds defend their nest and fledged young, sometimes aggressively – on rare occasions, they are known to swoop and snap their bills at intruders. Talk about a power couple!

After leaving the nest, young Powerful Owls are dependent on their parents for several months.

5. They’re under threat

Like many Australian birds, Powerful Owls rely on tree hollows to nest and raise their chicks in – and these hollows can take hundreds of years to form.

• Widespread logging and land-clearing means more trees are being cut down to make way for our sprawling cities, and critical nesting trees are becoming a rarity. Habitat destruction and fragmentation is driving the decline of hollow-nesting species, and Powerful Owls are now listed as Vulnerable to extinction in NSW and Victoria.
• Slow acting, lethal second-generation rodenticides (SGARs) are also deadly for Powerful Owls and other predatory birds – as they can kill not only the rats and mice they are targeting, but anything that eats them. Sadly, this includes Powerful Owls.

In a 2021 study, BirdLife Australia analysed liver samples from 38 Powerful Owl specimens to test for rodenticide poisoning. Disturbingly, we found that rodenticide was present in 37 of the 38 samples – with the anticoagulant rodenticide chemicals found in common household rat and mice baits detected in all but one specimen. Almost 60% of samples had levels of poison high enough to cause impairment, making the birds more vulnerable to other threats like car strikes.

How to help Powerful Owls 

Show that you give a hoot about Powerful Owls by practising bird-friendly rodent control at home and joining our campaign to get these bird-killing rodent poisons out of the food chain by regulating their use.

The Australian Pesticides and Veterinary Medicines Authority (APVMA) will soon release its decision on the use of rat poisons, giving us a chance to ensure our concerns about these dangerous products are heard. Sign our petition and stay tuned to join the conversation and help ensure these harmful substances are removed from store shelves!

Learn how BirdLife Australia’s citizen science Powerful Owl Project is helping us better understand the ecology of our urban Powerful Owl populations and how best we can protect them.