Brown Fish Owls

Brown Fish Owls (Bubo zeylonensis or Ketupa zeyolensis) are a species of owl that belong to the family Strigidae (typical owls).

Physical Description

The Brown Fish Owl is a large owl with prominent "ear" tufts, typically around 55 centimeters (22 in.) in length and weighing 2–2.5 kilograms (4.4–5.5 lb.) when fully grown. Subspecies differ in size and males are smaller than females, with the smallest birds not quite 50 cm (20 in) long and weighing as little as 1,100 grams (39 oz).

The upperparts are reddish brown and heavily streaked with black or dark brown. The underparts are buff to whitish, with dark streaks and finer brown barring. The throat is white and can be conspicuously puffed, while the facial disk is indistinct. The irides are yellow, the feet a duller yellow, and the bill is dark. Sexes do not differ in appearance except for size.

Call

Its calls are described as a deep tu-hoo-hoo or a soft huphuphuphuphuphup or a loud huhuhuhuhuhuhu.

Ecology

This species is an all-year resident throughout most tropical and subtropical parts of the Indian Subcontinent to Southeast Asia and southeastern China; it is also found in Sri Lanka. West of its main range, it is patchily distributed to the Levant (possibly extinct) and southern Asia Minor (recently rediscovered). It inhabits mainly the lowlands, in well-wooded habitat, from open woodland to dense forest as well as in plantations; in the Himalayas foothills it ranges into submontane forest up to 1,500 meters ASL or so but not higher. 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.

This species is chiefly nocturnal, but it can often be found by the small birds that mob it while it is roosting in a tree. It feeds mainly on fishes, frogs and aquatic crustaceans; amniotes, in particular terrestrial ones, are seldom taken. If hungry, Brown Fish Owls will scavenge carrion.

The prehistoric subspecies B. insularis is sometimes included in the Brown Fish Owl. If this is correct, the different foot anatomy, more similar to that of a typical eagle-owl, would imply that the population had shifted back to terrestrial prey. A likely prey item in this case would have been the Sardinian pika (Prolagus sardus). It has been conjectured that the owls disappeared with their prey due to climate change, but the giant pikas of Sardinia and Corsica still existed around 1750, finally succumbing to habitat destruction, introduced predatory mammals and overhunting soon thereafter.

Brown Fish Owls breed from November to March. The clutch is one or two eggs, often placed in an old stick nest of other birds, otherwise in a rock crevice or similar. Incubation is 38 days or somewhat less, and the young fledge after about 7 weeks.

The Brown Fish Owl is not considered a threatened species by the IUCN. Being a large predatory bird, it is only rarely found at a high population density. Habitat destruction will eventually cause the species to desert a region, and probably because of this it seems to be extinct as a breeding bird in Israel nowadays.