Brown fish owl

Appearance

This species is a large owl, but it is intermediate in size between other fish owls. It ranges from 48 to 58 cm in length and in wingspan from 125 to 140 cm. Weight can vary considerably, reportedly ranging from 1.1 to 2.5 kg. Some of the variability is attributed to the range of sizes across the subspecies. Also, females are invariably at least somewhat larger than males and condition of birds is variable. It has prominent ear tufts but as in all fish owls, their tufts hang to the side of the head and have a scraggly look.

The upperparts are rufous brown and heavily streaked with black or dark brown. The underparts are buffy-fulvous to whitish, with wavy dark brown streaks and finer brown barring. The throat is white and can be conspicuously puffed, while the facial disk is indistinct. The irides are golden yellow, the feet a duller yellow, and the bill is dark. Sexes do not differ in appearance except for size. Second-year fish owls of this species tend to be somewhat paler than full adults. Compared to the tawny fish owl, which they meet in range in Laos and Vietnam, it has a browner and less rufous overall color and a less pale face. The tawny also does not have barring as does the brown fish owl, it has feathering over two-third of its tarsus, whereas the brown is featherless on its legs, and has a yellowish band across its back absent in the brown species. Compared to the buffy fish owl, with which they may meet in the southeastern reaches of its range, the brown fish owl is slightly larger with a hue that's clearly browner and that species lacks the vermiculations and bars on the underside of the brown species.

Distribution

This species is an all-year resident throughout most tropical and subtropical parts of the Indian Subcontinent to Southeast Asia and adjoining regions. West of its main range, it is patchily distributed to the Levant and southern Asia Minor. The typical habitat of brown fish owls is forest and woodland bordering streams, lakes or rice fields. It inhabits mainly the lowlands, from open woodland to dense forest as well as in plantations; in the Himalayas foothills it ranges into submontane forest up to 1,500 m ASL or so but not higher. It frequently spends the day in stands of bamboo or other large shady trees. They be found around water reservoirs, along canals, on the outskirts of villages and along sea coasts. Western birds are found in semiarid landscape and may breed in oases in arid regions. Regardless of habitat, it rarely strays far from larger bodies of water such as rivers and lakes.

Reproduction

Brown fish owls breed from November to April, with activity tending to peak a bit earlier in the north of their breeding range and a bit later in the more tropical south of their breeding range. The breeding season is concurrent with the dry season, which has the benefit of low water levels and thus crabs and fish being more readily assessible. However, most other owls and diurnal raptors also primarily breed in the dry season as well. As owls do not build nest, brown fish owls are somewhat opportunistic when it comes to nesting sites. Brown fish owls frequently nest in shady spots such as old-growth mango trees, fig trees, including "Ficus religiosa" and "Ficus benghalensis", "Shorea robusta" and other large trees in lowland forests. Outside of the bare surface of large branches, nests are often in spots such as overgrown eroded ravines and steep riverbanks with natural holes. However, it may also nest near suitable villages, along wet roadsides, "jheels", canals and rice fields. Usually nest are large natural holes, in hollows or at the base of large branches. Deserted nest built by fish eagles and vultures are also sometimes used as nesting locations. Other nesting sites have included rock ledges, caves in shady cliff faces and stone ruins. The clutch is two or occasionally just one egg. 10 eggs in India averaged 58.4 mm × 48.9 mm in sizes, with eggs of fish owls to the north averaging slightly larger. Incubation is 38 days or somewhat less, and the young fledge after about 7 weeks. The downy chicks are mostly an off-white color and develop into a paler version of adults by their second year.

Food

This species is very nocturnal but it can often be located by the small birds that mob it while it is roosting in a tree. However, in some areas it may be semi-diurnal and has been seen hunting during daytime, especially in cloudy weather. Brown fish owl primarily hunt by stationing itself on a rock overhang or hanging perch over water, or by wading into shallow waters. It grabs food by gliding over the water, nearly skimming it with its feet and grabbing its prey by quickly extending its long legs. It feeds mainly on fishes, frogs and aquatic crustaceans, especially "Potamon" crabs.