Powerful Owl

## Description

The powerful owl (Ninox strenua ), a species of owl native to south-eastern and eastern Australia, is the largest owl on the continent. It is found in coastal areas and in the Great Dividing Range, rarely more than 200 km (120 mi) inland. The IUCNRed List of Threatened Species also refers to this species as the powerful boobook. An apex predator in its narrow distribution, powerful owls are often opportunists, like most predators, but generally are dedicated to hunting arboreal mammals, in particular small to medium-sized marsupials. Such prey can comprise about three-quarters of their diet. Generally, this species lives in primary forests with tall, native trees, but can show some habitat flexibility when not nesting. The powerful owl is a typically territorial raptorial bird that maintains a large home range and has long intervals between egg-laying and hatching of clutches. Also, like many types of raptorial birds, they must survive a long stretch to independence in young owls after fledging. Unlike most raptorial birds, however, male powerful owls are larger and stronger than females, so the male takes the dominant position in the mating pair, which extends to food distribution.

## Appearance

The Powerful owl is native to south-eastern and eastern Australia and is the largest owl on the continent. It is found in coastal areas and in the Great Dividing Range rarely more than 200 km (120 mi) inland. An apex predator in its narrow distribution, the Powerful owl is often an opportunist like most predators, but generally hunts arboreal mammals, in particular small to medium-sized marsupials. It is a typically territorial raptorial bird that maintains a large home range and has long intervals between egg-laying and hatching of clutches. Unlike most raptorial birds, male Powerful owls are larger and stronger than females and so the male takes the dominant position in the mating pair, which extends to food distribution.

## Distribution

Powerful owls can be found from Eungella and the Dawson River in Queensland south to the central highlands of Victoria and west to Mount Burr in South Australia, the range terminating around Portland, Victoria. They inhabit tall, humid forests ranging through to some drier woodlands in northern Victoria and the western slopes of New South Wales and Queensland. Powerful owls can be found in wooded mountain gullies, forested ravines, wetter, heavily timbered sub-coastal ranges, coastal forests and woodland, and coastal scrub. They will also occasionally range into plantations, mainly of pine or native tree species, and urban and rural parks and gardens.

## Behavior

These birds live in breeding pairs and have been observed roosting singly, in pairs, and in family groups of 3 or 4. They frequently roost during the day on branches in tall, open trees, often while still holding the prey caught the prior night. Powerful owls typically fly in a slow and deliberate way on their large wings. They are top nocturnal predators of the forests and woodlands in their range. The vast majority of prey is taken from trees, often in or near the tree canopy. Powerful owls generally glide from perch to perch, watching for prey activity in surrounding trees until potential prey is detected. If the prey becomes aware of the owl too soon, a tail-chase may ensue but many prey species (even diurnal ones) can successfully evade the large predator. Powerful owls frequently take apart prey and consume piecemeal. At daytime perches, they occasionally wake to consume food until leaving the roost in the evening. These birds communicate with the help of various vocalizations. The males' song is an impressive low, rather mournful-sounding and far-carrying double-hoot, 'whoo-hooo'. Females have a similar call but have a higher-pitched voice. Duets are frequently heard at the onset of breeding; unpaired males frequently call much more regularly than paired ones.

## Diet

Powerful owls are carnivores. Their diet consists mainly of arboreal mammals such as the greater glider, ringtail possums, brushtail possums, koala, sugar glider, and feathertail gliders. They may also take roosting birds, insects, and ground-dwelling mammals.

## Reproduction

Powerful owls are monogamous mate for life. They breed in the Australian winter, mainly in May and June. The nest is usually located a large hollow in a tree and lined with decaying debris and leaf litter. The female lays 2 (sometimes 1) eggs and incubates them about 36 to 38 days. The male does all hunting and sometimes aggressively defends the nesting during the brooding stage. Owlets are born altricial; they are mostly off-white with a greyish-brown mask and grey on the wings and coverts. The young fledge at 6 to 8 weeks but typically accompany and are fed by their parents for several months even until they can fly well; the total dependence period usually lasting 5 to 9 months before independence, and sometimes into the next breeding season.

## Population

### Population threats

These birds are not threatened but they suffer from habitat loss, poisoning, and disturbance. Powerful owls are often victim to and occasionally even injured by heavy mobbing by larger passerines such as currawongs, magpies, and crows and ravens.

### Population number

According to the IUCN Red List, the total Powerful owl population size is around 3,250-4,250 individuals, equating roughly to 2,200-2,800 mature individuals. Specific populations have been estimated in such areas: fewer than 500 pairs (1,000 individuals) in Victoria; approximately 1,000-1,500 pairs in north-east New South Wales (approximately 2,000-3,000 individuals) and approximately 125 pairs (250 individuals) in south-east New South Wales. Overall, currently, Powerful owls are classified as Least Concern (LC) on the IUCN Red List and their numbers today are stable.

## Fun Facts for Kids

Powerful owls usually use several perches that may be occupied intermittently for years at a time.

The closest relatives of the Powerful owl are the Barking owl and the Southern boobook and all of them are categorized as ‘hawk owls’.

Powerful owls are so fond of possums that a breeding pair may consume as many as 250 of these animals per year.

Powerful owls have very large breeding territories. Even when food is abundant, the territories are at least 800 to 1,000 ha (2,000 to 2,500 acres) but when food is scarce, their territories tend to be larger. On average, nests of breeding pairs are found from 5 to 20 km (3.1 to 12.4 mi) apart.

Male Powerful owls can fight over breeding rights with females and over territories if needed.