page_title: Powerful owl
section_title: Breeding
hierarchical_section_title: Powerful owl / Behaviour / Breeding
caption_attribution_description: English: powerful owl nestlings, Sylvan Grove Native Garden, Picnic Point, NSW
context_page_description: The powerful owl is a species of owl native to south-eastern and eastern Australia, the largest owl on the continent. It is found in coastal areas and in the Great Dividing Range rarely more than 200 km inland. The International Union for Conservation of Nature 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.
context_section_description: The powerful owl breeds in the Australian winter, with breeding occurring mainly in May and June and brooding at the nest into September. The breeding behaviour of powerful and rufous owls appears to be highly similar. The breeding territory of powerful owls is large. Even when food is abundant, territories are at least 800 to 1,000 ha (2,000 to 2,500 acres). When food is scarce, 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. Males have been recorded fighting over breeding rights to females and territories. The nest is most often a large hollow in a tree. Nests have been recorded at 8 to 30 m (26 to 98 ft) above the ground but are most often at least 10 to 15 m (33 to 49 ft) 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 54 mm × 45 mm (2.1 in × 1.8 in). 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 females appears to do all incubation and the incubating stage is 36 to 38 days. The male does all hunting and sometimes aggressively defends the nesting during the brooding stage. In other owls that show aggression towards humans during nesting, it usually the female who is the main aggressor, although in other owls the females are larger with stronger strikes, whereas in the powerful owl, the males are the larger and more powerful sex. Occasionally, females may abandon their nest if disturbed. In general, the slightly smaller rufous and notably smaller barking owl both display more frequent and more spiritedly aggressive nest defense than the powerful owl does. Young powerful owls are mostly off-white with a greyish-brown mask and grey on the wings and coverts, obviously distinct from the adult plumage. The young fledge at 6 to 8 weeks. However, the young typically accompany and are fed by their parents for several months even into the stage that they can fly well, the total dependence period usually lasting 5 to 9 months before independence, and sometimes into the next breeding season. Although there are practically no predators of this species except, in very rare, anecdotal instances, wedge-tailed eagles (Aquila rapax) and powerful owls have been recorded killing each other in territorial and breeding skirmishes. Also, they are often victim to and occasionally even injured by heavy mobbing by larger passerines such as currawongs, magpies, and crows and ravens. In one case, a pair of Australian ravens (Corvus coronoides) attacked and killed a powerful owl, likely in order to defend themselves and their nest.
caption: The young of the powerful owl leave the nest a few weeks after hatching but frequently are cared for over several months after dispersing from the nest.
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