By Jo Gregson (Head Birdkeeper)
First Published in The Avicultural Magazine Vol. 92 No. 1
Copyright © 1986 Avicultural Society, Published with Permission

There are four species of the genus Ketupa distributed from the Middle to the Far East but the RearingBrown Fish OwlKetupa zeylonensis is by far the most widespread, four subspecies occupying a range from Israel in the west through India, Burma and Ceylon to China in the east.

It inhabits wooded country, seeking out overgrown ravines and steep banks near rivers and streams in which it catches the fish and crabs that form the main part of its diet, though small mammals and birds are also taken.

This very handsome owl is 22 in (0.55 m) long. The sexes are alike in plumage which is generally a reddish brown above, with black streaks and beige and white spots; underneath it is whitish with brown streaks and bars. [ts feet and claws are especially adapted to catch and hold irs slippery prey and resemble those of the Osprey.

In the wild, the breeding season is from December to March, generally in February.

This Fish-Owl was kept quite commonly in aviaries but the numbers have dwindled in recent years, probably due to the restrictions on importing and keeping birds of prey. This species has laid eggs in several collections but we believe that it has never before been reared successfully in Britain, though the closely related Javan Fish Owl Ketupa ketupu was bred at London Zoo in 1967 (Avicultural Magazine, 1968, pp. 17-18).

A male Brown Fish Owl had been in the collection here since 1967; in April 1981 it was paired with a seven-year old female received in exchange from 'Birdworld', Surrey.

The pair live in an unheated outdoor flight, constructed of 1 in (2.5 cm) chain link, laced on to a tubular metal framework, measuring 20 x 10½ x 10½ ft high (6.00 x 3.20 x 3.20 m). Aviary furniture includes natural perching, natural tree stumps, a large Bay shrub Laurus nobilis, and a raised feeding ledge. At the base of the shrub is a large water tray. A roofed, wood-partitioned area as wide as the aviary extends 5 ft (1.52 m) beyond the back of the flight. The roofing also projects forward some 5 ft in order to provode outdoor shelter. The nest-box 6½ ft (1.97 m) above the floor is positioned inside the partitioned area aligned with an access hole (for the owls) measuring 1½ x 1 ft high (0.45 x 0.30 m). Keeper access is by means of lower small hinged door. Since the aviary is sandwiched between other similar owl flights, there are two entrance/exit doors in either side as well as a seldom-used door in the front of the aviary.

In January 1982 the pair began to use an open-fronted nest-box measuring 30 x 16 x 24 in high (0.75 x 040 x 0.60 m) with a 6 in (0.15 m) upstand. A few days later one thin-shelled broken egg was found on the aviary floor. Despite constant improvements to the birds' diet, the clutches laid in 1983 and 1984 were both thin-shelled and broken. The nest-box proved unsuitable for the purposes of removing eggs undamaged and at the end of 1984 a newly-designed nest-box was fitted in the hope that we would be able to remove an egg before it was broken. The new box was open-topped and measured 24 in x 24 in x 12 in high (0.60 x 0.60 x 0.30 m), with a 12 in square front drop flap allowing easier access to the eggs. The floor of the box (drilled in places for drainage) was layered with peat and scattered with old pellets!

On 9th January 1985 one egg was removed for artificial incubation; a second egg had already been cracked and failed to hatch. The incubator was run dry until the chick had moved into the air space on 7th February. The next morning the chick had hatched. It was very strong with eyes partially open, but its navel had not yet healed. The chick may have escaped too soon from its thin shell and not had sufficient time for the yolk sac to be completely withdrawn into the abdomen. Fortunately after swabbing it with antiseptic, it healed over without any developing infection.

The chick took its first feed at midday. It comprised trout and soft pieces of mouse. Thereafter it was fed approximately every two hours from 7 a.m. to 11 p.m. each day and tweezers were used to hold the food; SA37, a vitamin supplement, was dusted onto one feed every fourth day.

For the first two days the chick was kept in the incubator, after which it was placed in a brooder. Two 60-watt light bulbs supplied ample heat.

The first small pieces of mouse bone were fed on the fourth day. Fur and feather were fed from the eighth day and fish were filleted before feeding. By day 15, the chick was covered in quills and therefore one 60-watt light bulb was exchanged for a 25-watt bulb. At 20 days it was beak clicking and hissing when disturbed, as a means of defence.

Much to everyone's surprise, the first pellet was not regurgitated until day 26 after which a pellet was produced almost every other day. Once we were sure it could pass pellets regularly, whole mice were fed.

Food was refused on the 33 rd day and the chick became very excited, jumping out of its box, head bobbing, wings flapping and using its feet to hold food and tear up paper on the cage floor. It fed of its own accord for the first time on day 42. A few days later a large water bowl was placed on the cage floor into which it leaped almost immediately. Thereafter it remained in or around the bowl most of the time.

By day 48 the chick required no further heat. When it could perch confidently, it was moved to a large flight on day 81.

The juvenile bird sported yellow, turning to grey, down until it was replaced by the adult plumage.

As described above, the Brown Fish Owl Ketupa zeylonensis has been bred by Paignton Zoological and Botanic Gardens and this is believed to be the first success in this country. Anyone knowing of a previous breeding in Great Britain or Northern Ireland or of any other reason that would disqualify this claim, is asked to write to the Hon. Secretary.