Powerful Owl

The **powerful owl** (*Ninox strenua*) is a species of owl native to south-eastern and eastern Australia, the largest owl on that continent. It is found in coastal areas, the Great Dividing Range rarely more than 200 km (120 mi) inland. The International Union for Conservation of Nature (IUCN) Red List of Threatened Species also refers to this species as the **powerful boobook**. An apex predator in its narrow distribution, the powerful owl is often an opportunist like most predators, but generally is 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 bird, they must survive a long stretch to independence in young owls post-fledging. Unlike most raptorial birds, however, 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.

## Description

The powerful owl has a long tail and a small head, lending it an atypical silhouette for an owl and imparting a more hawk-like appearance than any other large owl. The protruding bill and distinct brow ridges enhance the hawk-like appearance of the species. The facial disc is ill-defined. The upperparts are a dark gray-brown colour, mottled and barred with whitish. The underparts are white with bold grey-brown V-shaped barring. The tail has six narrow white bars contrasting with grey-brown. This species has large yellow eyes, with greyish feathering down to the base of the toes and feet of a dull yellow color. They are aptly named, with very powerful and heavy claws. This owl is the largest species of the "hawk owl" group found in much of Asia and the Australasian region, all included in the genus *Ninox*. It can be considered, along with its sister species the rufous owl (*Ninox rufa*), as Australia's analogue to the *Bubo* genus.

This species measures 45 to 65 cm (18 to 26 in) in length and spans 112 to 135 cm (44 to 53 in) across the wings. Unlike in a vast majority of owl species, the male is slightly larger than the female on average. Most owls and raptors have reverse sexual dimorphism (RSD) whereas the powerful owl is considered to have normal sexual dimorphism (NSD) as do a majority of living (non-raptorial) birds. Body mass in males have been reported at 0.99 to 2.22 kg (2.2 to 4.9 lb), with 13 males averaging 1.45 kg (3.2 lb), while females can weigh from 1.04 to 1.6 kg (2.3 to 3.5 lb), with an average in 9 females of 1.25 kg (2.8 lb). Among all the owls in the world, the powerful owl is the ninth longest from bill-to-tail, the tenth heaviest and the eighth longest winged. Its body mass is about the same on average as the great horned owl (*Bubo virginianus*) but it has a proportionately much longer tail and wings than that species. The wing chord length further illustrates slight sexual dimorphism in favor of the male, with the male measuring 397 to 434 mm (15.6 to 17.1 in) and the female measuring 381 to 410 mm (15.0 to 16.1 in). The tail can be 280 mm (11 in) or more in length, the fifth longest of any owl with only the great grey (*Strix nebulosa*) and ural owls(*Strix uralensis*) having proportionately longer tails. As a relatively geographically restricted species, there are no subspecies and no known geographic variation in the powerful owl. In comparison to the barking owl (*Ninox connivens*) it is much larger and lacks that species' white-spotted smoky-brown coloration on the upperparts and dark grey to rusty streaks on a whitish background on the underside. The other larger and relatively powerful owl found in Australia, the rufous owl, is not found in the same range in the wild so poses no identification problem.

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