Barred eagle-owl

Appearance

The barred eagle-owl is a fairly large owl but relatively small eagle-owl, this species ranges from 40 to 48 cm in length. There is almost no size sexual dimorphism in this species and adjacent island subspecies vary dramatically in size, both unusual attributes for eagle-owls. It is most distinctive due to its barred underparts, large but sideways-slanting ear tufts, a white bar running from the eyebrows through the front of the eart tufts and much more heavily marked breast than belly. The face and lores are a dirty grayish white colour. The eyes are usually a dark brown colour, but occasions where this species has had yellow eyes have been reported.

The bill and cere are pale yellow, with an occasional greenish tinge to the cere. The upperparts are grey-brown, crossed and mottled with several zigzag bars of rufous-tawny colour, being broadest on the back. The upper-tail is dark brown with about six whitish or tawny bars. The tarsi are feathered to the toe joint. The juvenile barred eagle-owl are pure white in their natal down. Whitish mesoptile stage, in transition to adult plumage, is still a dirty white but is banded with brown on the wings and tail and the ear tufts are much shorter than on mature birds.

Naming

*"B. sumatranus sumatranus" - Also referred to as the "nominate subspecies". Found on Sumatra, Bangka and the Malay Peninsula. This race is relatively small and the bands on the belly are not as dark or as widely spaced as on Javan birds. The wing chord is 323 to 358 mm. The tail is 183 to 190 mm. Body mass of one bird was reportedly 620 g.
⤷ "B. sumatranus strepitans" - Found on Java and Bali. This race is considerably larger than the nominate race with broader and dense barring on the underparts. The wing chord is 370 to 417 mm. Weight in this race can reportedly range from 1,427 to 1,606 g, with an average of 1,525 g.
⤷ "B. sumatranus tenuifasciatus" - Found only on the island of Borneo. This race is similar in size to the nominate race but its bands are much finer and closer together. The wing chord is 323 to 350 mm.

Distribution

It is found in Brunei, Cocos Islands, Indonesia, Malaysia, Myanmar, Singapore, and Thailand. Its natural habitat is subtropical or tropical moist lowland forests. It typically is a resident of evergreen forests with pools or streams, but also ranges into large gardens with tall, densely foliated trees, such as the Bogor Botanical Gardens found in West Java as well as wooded groves in cultivated country, both sometimes not far from human habitations. It usually ranges in elevation from sea-level to roughly 1,000 m but can range up to about 1,600 m or more at locations like Mount Gede in West Java and Mount Singgalang in West Sumatra.This species is found at low densities with large territories, as can be expected for most large birds of prey, but it is not uncommon. It is less common than the buffy fish owl on Java and Sumatra.

Reproduction

This species probably pairs for life. Barred eagle-owls seems to be very attached to a particular nesting site. If not disturbed, they will occupy the same territory for several years and, if one partner dies, the surviving mate will maintain the same territory with another owl parent. This species nests either in large tree cavities or, in Java and Sumatra, on top of the large fern "Asplenium nidus". The only other known nesting location has been at the base of an epiphyte large enough to form a sheltered hollow against a large branch. Only one egg is laid, the smallest clutch size of any owl, tied with the buffy fish owl and the spot-bellied eagle-owl, which have also only been recorded with a clutch of only one egg. The egg is white with an oval shape, measuring about 59.8 mm × 47.9 mm. In Java, eggs have been found from February to April and nests with young from May to June. In Sumatra, nestlings or dependent young have been observed in March through May and in Borneo, young have been observed in February through March.

Food

What little is known of the dietary habits of the barred eagle-owl indicates it has a very broad, opportunistic diet. Much like other eagle-owls, the barred eagle-owl has large, powerful feet for its size with large, heavy, slightly curved talons, indicating a diverse diet that can extend to relatively large prey given the opportunity. Known foods have included large insects, birds, small mammals, and reptiles, largely snakes. In one instance, an eagle-owl preyed on a young crab-eating macaque, which even at a young age is likely to be as large or larger than the eagle-owl. When held in captivity, this species is not choosy and will consume fresh meat from fish, birds and mammals. In one instance, when kept in an aviary with a changeable hawk-eagle, the owl killed and consumed the hawk-owl despite its similar body size, indicative of a ferocity and lack of discrimination in regards to prey species, once again similar to other eagle-owls.