Powerful owl

The powerful owl has a long tail and a small head, giving 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. 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 (N. rufa), as Australia's analogue to the genus Bubo. 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 and the female measuring . The tail can be 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 colouration 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. Voice The male powerful owl's song is an impressive low, rather mournful-sounding and far-carrying double-hoot, whoo-hooo, each note lasting a few seconds at least, broken up by a brief silence and the second note being usually higher pitched than the first. The female has a similar call, but has a higher-pitched voice. Duets are frequently heard at the onset of breeding. Unpaired males frequently call much more regularly than paired ones. ==Distribution and habitat==

Their range is from Eungella and the Dawson River in Queensland south to the central highlands of Victoria and west to Mount Burr in South Australia, with the range terminating around Portland, Victoria. The habitat of the powerful owl is tall, humid forests ranging through to some drier woodlands in northern Victoria and the western slopes of New South Wales and Queensland. They can be found in wooded mountain gullies, forested ravines, wetter, heavily timbered subcoastal ranges, coastal forests and woodland, and coastal scrub. They prefer wetter, more timbered areas such as sclerophyll forests. Although usually associated with subcoastal forest, they can be found on inland mountain slopes occasionally. This is especially the case with young owls after dispersal before they can establish their own breeding territories. Recent mapping work has shown that streams between ridges covered with Eucalyptus forest are often prime habitat for this species. They also occasionally range into plantations, mainly of pine or native tree species, and urban and rural parks and gardens. ==Behaviour==

, New South Wales The powerful owl lives permanently in breeding pairs once in adulthood. They have been observed roosting singly, in pairs, and in family groups of three or four. They frequently roost during the day on branches in tall, open trees, often while still holding the prey caught the prior night. Several perches are used, and may be occupied intermittently for years at a time. The powerful owl typically flies in a slow and deliberate way on its large wings. These prey species vary extensively in body size, from the feathertail glider, which has an adult weight merely of to the koala, typically weighing , though juveniles are mainly taken in large prey species. The average estimated prey weight per one study was approximately . However, another two studies stated the mean prey weight as and . Not infrequently, prey weight averages between 50 and 100%, whereas, in most other raptors, including large owls, there seems to be a "rule" that most prey weighs 20% or less of the raptors' own weight. The mean weight of prey for powerful owls can be up to 10 times greater relative to their body weight than the mean prey weight of similarly sized northern owls, such as great grey or great horned owls. The most largely taken prey species in many regions are adults of common ringtail possum (Pseudocheirus peregrinus) which can weigh around . Larger common brushtail possums (Trichosurus vulpecula) of all ages can be taken, but young specimens are preferred since they are abundant in spring and easier to catch than adults around in weight. Not infrequently taken are the black (Pteropus alecto) and grey-headed flying foxes (Pteropus poliocephalus), the largest of Australian bats, although smaller bats have also been killed. In one study, the most frequently killed bird prey species were pied currawong (Strepera graculina) and crimson rosella (Platycercus elegans) and avian prey taken as a whole was estimated to average . Insects (such as crickets and beetles) and crayfish may supplement the diet and are typically taken on the wing. Powerful owls frequently take apart prey and consume it piecemeal. At daytime perches, it occasionally wakes to consume food until leaving the roost in the evening. The three largest Ninox owls are the only owls known to exhibit the behaviour of mantling over food while roosting during the day. One theory is that the male regularly holds onto the prey during the day, and thus can control the distribution of food to the family in keeping with his dominant size; whereas in most owls, females are larger and more dominant, and thus the male could not display such behaviour as keeping food from his larger mate. The nest is most often a large hollow in a tree. Nests have been recorded at above the ground but are most often at least high. The nesting material includes decaying debris and leaf litter. Eggs are oval and dull white. The clutch is most often two, but occasionally includes only one egg, and rarely three are laid. The egg averages about . The eggs are typically laid directly on the rotten wooden floor of the nesting cavity; owls do not build a nest. Egg-laying intervals are up to 4 days between the first and second egg, an unusually long interval for an owl. The female appears to do all incubation and the incubating stage is 36 to 38 days. ==Conservation status==

Powerful owls are not listed as threatened on the Australian Environment Protection and Biodiversity Conservation Act 1999. However, their conservation status varies from state to state in Australia. For example: • The powerful owl is listed as "threatened" on the Victorian Flora and Fauna Guarantee Act (1988). Under this Act, an Action Statement for the recovery and future management of this species has been prepared. • On the 2013 advisory list of threatened vertebrate fauna in Victoria, the powerful owl is listed as vulnerable. • On the New South Wales Threatened Species Conservation Act 1995, the powerful owl is scheduled as "vulnerable". These owls do not do as well in heavily developed areas or in monocultures even if the plantation is made up of a native tree. This is largely because its prey is dependent on native and diverse forests. ==In popular culture==

The Big Powerful Owl is an sculpture of a powerful owl in the Canberra suburb of Belconnen. ==References==