Tawny Fish-owl

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Image:TawnyFishOwl.jpg

Common Name: Tawny Fish-owl
Scientific Name: Bubo flavipes

Size: 19-24 inches (48-61 cm); Wingspan: 62.9 inches (160 cm)

Habitat: Asia; found in subtropical to temperate forests in Bangladesh, Bhutan, China, India, Laos, Myanmar, Nepal, Taiwan, and Vietnam. They inhabit the Himalayan foothills from Kashmir and Garhwal east to the mountains of Laos and Vietnam and in southern China up to Chekiang and Anhwei.

They require forest tracts, floodplains or foothills bearing mountain streams.

Status: Least Concern. Global population: Unknown amount of adult individuals with a stable population trend. National population sizes have been estimated at < c.100 breeding pairs in China and < c.100 breeding pairs in Taiwan (Brazil 2009).

Diet: Mostly fish, crabs, shrimps, crayfish and frogs. The primary food of tawny fish owls in one study from Taiwan was freshwater crabs (apparently of the Candidiopotamon genus) which made up 62.8% of the diet, followed by the Asiatic toad (Bufo gargarizans), at least three other frog species, then fish and Eriocheir mitten crabs. The toads were taken considerably more regularly than other frog species, although far less abundant in number in the stream wetlands there, due to their larger sizes. More terrestrial prey is by no means avoided though and the species may also hunt lizards, snakes, and small mammals such as moles, and particularly rodents (such as the bamboo rats (Rhizomys)). It also preys on birds including Mandarin ducks (Aix galericulata) in Taiwan and has preyed upon large ground birds such as junglefowl (Gallus ssp.), pheasants and eared pheasants (the latter sometimes weighing more than 2 kg (4.4 lb)).

The tawny fish owl is at least partially diurnal in activity, with daytime activity mainly occurring in the late afternoon and they may be seen actively hunting before nightfall especially on cloudy days. However, before the afternoon they tend to be sluggish during the day. If disturbed or threatened, these owls tend to sit tight and not take flight. Like most owls, they usually choose inconspicuous perches during the day to avoid detection. They usually hunt by swooping down to the water to capture fish from the surface and are reportedly surprisingly active in their hunting style and are not dissimilar in the hunting methods to those used by diurnal fish-hunting raptors such as fish eagles, sea eagles and ospreys.

Nesting: Males and females are alike however males tend to be up to 8% heavier than females. It is a large fish-owl with prominent horizontal ear-tufts. Facial disc orange-rufous with indistinct dark border; above, rich orange-rufous or tawny with broad striping.

Tawny fish owls are highly solitary and territorial as are a majority of owls. The breeding season is November to February in India and December to February in Assam. Nest locations found have included large holes in river banks, caves in cliffs and the fork or crotch of a large tree. As in all owls, tawny fish owls do not build a nest so merely lay their eggs on the bare ground of whatever surface they use. They also have been known to nest in abandoned nests built by Pallas's fish eagles (Haliaeetus leucoryphus). Usually two eggs are laid, but sometimes only one is. Greater details of the reproductive biology are not currently known although are presumed to basically be similar to those of other fish owls.

Cool Facts: Compared to eagle owls of similar length, fish owls tend to be even shorter in tail length and even heavier in build, have relatively larger wings (the tawny is particularly chunky in shape), have considerably longer legs, and have a rough texture to the bottom of their toes. At least the latter two features are clear adaptations to aid these owls in capturing fish.

Unlike fish-eating diurnal raptors who will not submerge any part of their body while hunting, fish owls will wade into shallow water, hunting on foot. Unlike most owls, the feathers of fish owls are not soft to the touch and they lack the comb and hair-like fringes to the primaries, which allow other owls to fly silently in order to ambush their prey. Due to the lack of these feather-specializations, fish owl wing beats make sounds. The lack of a deep facial disc in fish owls is another indication of the unimportance of sound relative to vision in these owls, as facial disc depth (as well as inner ear size) are directly related to how important sound is to an owl's hunting behavior. Similar adaptations, such as unwillingness to submerge beyond their legs and lack of sound-muffling feathers are also seen in the African fishing owls, which do not seem to be directly related.


Found in Songbird ReMix Owls of the World Volume 2

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