Buffy fish owl

Appearance

The buffy fish owl is a fairly large owl but is the smallest of the four species of fish owl. In total length, this species can range from 38 to 48 cm. Body mass can range from 1,028 to 2,100 g, with an average weight of 1,224 g.

This species is yellowish-brown overall, with considerable variegating with pale buff. The feathers are edged tawny and the wings and tail are broadly barred yellowish and dark brown. The wings are distinctly rounded in shape when this species is seen in flight.

The underparts are a yellow-brown, rich buff or fulvous color with broad blackish shaft-stripes. The legs are long and unfeathered. This species slightly overlaps in range with the brown fish owl, but that species is slightly larger and considerably more brown in overall color with stronger barring and vermiculations below.

Naming

*''B. ketupu ketupu'' - Found in the Malay Peninsula, Riau Archipelago, Sumatra, Borneo, Belitung, Java, Bali and much of Borneo. This race matches the description above. It is the only well-studied race and is seemingly the largest, slightly more so than ''aagaardi'' and considerably more so than the other two island races. The wing chord is 335 to 390 mm , the tail is 160 to 181 mm , the tarsus is 70 to 80 mm and the bill is 40 to 42 mm .
⤷ ''B. ketupu aagaardi'' - Found in southern Burma to peninsular Thailand and Vietnam. This race is similar to the nominate but is much paler, especially on the underparts. The wing chord is 315 to 354 mm , other than that it is of the same size as the nominate in linear dimensions.
⤷ ''B. ketupu pageli'' - Endemic to Sarawak on the east coast of northern Borneo. This race is similar to the noinate but is far more reddish in color, with some birds being a brick-red color. The wing chord is 310 to 330 mm .
⤷ ''B. ketupu minor'' - Found only on the island of Nias. This race is notably for its very small size. The wing chord is 295 to 300 mm .

Distribution

It is found from southern Burma and central India to the south and east to Cambodia, Laos and Vietnam, peninsular Thailand, the Malay Peninsula, the Riau Archipelago, Sumatra Brunei, Cocos Islands, Indonesia down to Java, Bali and Borneo. One specimen was recorded at Cocos Island off Australia, 1,050 km outside its regular range. Its natural habitat is wet tropical forests and other woody areas near water, including wooded banks of rivers, lakes and fish ponds and rich paddies. It can survive well close to human habitations but can also be found in desolate mangrove forests and other less-inhabited or uninhabited areas. It mainly lives in lowlands but can be found at up an elevation of 1,600 m.

Behavior

During the daytime, these owls shelter, often singly, in quite dark places, such as densely foliaged trees. Buffy fish owls are easily disturbed, quite the opposite of the highly stoic tawny fish owl, often being wide-awake before being spotted by a human observer.

Reproduction

Eggs have mainly been found in February through April, less commonly into May through July, as in western Java, and even in September through January in the Malay Peninsula. The buffy fish owl frequently nest on top of a large fern, but nests have also been recorded in the fork a tall bough covered in ferns and moss, on orchid beds and in tree holes.

More rarely, rocky sites have been used as nesting sites, even behind waterfalls. The nest is usually merely a scrap into the surface of a fern with no structure or lining, as owls do not build nests. Abandoned bird nests built by other species have been used, including those of brahminy kites.

Only one egg has ever been recorded in a buffy fish owl nest, giving them the smallest clutch size of any owl alongside the spot-bellied eagle owl, which has only ever been recorded with a single-egg clutch. The egg is round, oval and dull white. The average dimensions of eggs in western Java was 57.4 mm × 47 mm . Incubation of the eggs lasts 28–29 days and fledgling occurs after six weeks. This species is generally faring well for a large raptorial bird and has been inadvertently aided by commercial fisheries and ornamental ponds, which they visit by night to hunt. Sometimes, they incure persecution from owners of such ponds for taking stock.

Food

The largest part of its diet appears to consist of fish, crabs and frogs followed by reptiles, toads and crayfish. Their diet is not extensively studied but appears to be basically the same as those of the brown and tawny fish owls.

Rats, mice and large insects are also sometimes taken and even bats have been captured by this species. A small handful of prey has been identified to genera or species in Java: goldfish, the gold-ringed cat snake, puff-faced water snake, young false gharials, fruit bats, centipedes, black rats and red junglefowl, some of this prey such as the cat snake and junglefowl being of a fairly large size.

Like the brown fish owl but unlike most owls, this species has been recorded consuming carrion, including the remains of a crocodile and a Sunda stink badger. The buffy fish owl does not produce firm pellets as do most owls. Instead bones and frog and insect remains are ejected in pieces and fall to the ground below roost. Prey remains have only been found within the nest, never around or below the nest as is commonly recorded in other owls. The buffy fish owl hunts mainly from the bank, swooping down much in the manner of a fish eagle but never getting its feathers wet. It also walks into shallow streams and brooks, additionally snatching their main foods in such locations.