Abstract
The slender-billed cockatoo (Cacatua tenuirostris tenuirostris) is a rather unusual looking bird found in an area of southeastern Australia. Also known as the long-billed corella, this cockatoo's most distinguishing feature is its elongated upper mandible that it uses to dig about in the earth for roots, bulbs, and the like. The other race of the species, ( Cacatua tenuirostris pastinator), is found in part of southwestern Australia and is considered by some to be merely a form of the little corella ( Cacatua sanguinea). While some cockatoo species like the little corella are not uncommon in captivity and sometimes abundant in the wild, the slender-billed cockatoo is neither. The Breeding Bird Survey conducted by the San Diego Zoo recorded fifteen slenderbills in American Zoos in 1980. Of these none were captive hatched. The Encyclopedia of Aviculture edited by Rutgers and Norris states that these birds have been captive bred in the U.S. in the San Diego Zoo prior to 1970. The wild population of these birds is estimated to be only about thirty to forty thousand. This number is certainly dwarfed by the swarms of roseate cockatoos that exist in Australia.
The Birmingham Zoo has maintained a pair of these rare birds for eight years. Two attempts to rear chicks were made by the pair prior to 1981, both ending in failure. One time the chicks disappeared, presumably eaten by one or both adult cockatoos. The other time the chick they were raising was found dead with whole sunflower kernels impacted in its crop. For some odd reason, the parent birds did not regurgitate partially digested food this time and it resulted in the chick's death. Considering this unpromising track record, we opted to remove one chick for handraising and to leave the second with its parents when
they hatched their third clutch on April 3, 1981. Both were successfully reared. In 1982 two eggs were laid but one proved infertile. Since the parents were successful last year, we decided to let them have this year's chick. They are currently rearing it with no problems at all.
Before I detail the procedure used in handraising the chick I would like to briefly discuss our breeding and husbandry setup for the slender-billed cockatoo. Two cages have been used to raise young by the adult pair in 1981 and 1982 respectively. One measures 9' x 8' x 8' and the other 9' x 15112' x 8'. The latter being their current residence. Each of these cages has a small portal that leads to small indoor cages where they are fed and watered inside the building. The cockatoos utilize a wooden nest box (3 2" x 13" x 13") with a 4" hole. The box is hung on the side of the cage near the top and features a small side view door to permit observation of eggs and chicks. The viewing door is never used unless the adult birds are inside the building feeding and out of sight. This is due to the fact that anyone approaching the nestbox has the effect of upsetting the adults greatly when there are eggs or young in the box. The nesting substrate utilized is peat moss to depth of about three inches. It seems to do a good job of simulating the moist decaying wood that they nest on in tree cavities in the wild. Inside the box we have placed a branch for the birds to climb down to and up out of the nest. In addition, there is a branch leading to the nest hole from the outside since the hen has an irreparable right wing injury that rendered her unable to fly up to the nest. Fortunately, this injury hasn't impaired her ability to breed and raise young.
Over the last year the diet of our cockatoos has undergone considerable evolution. Starting from a fairly simple diet of sunflower seeds, finch seed, apple, banana, grapes, oranges, a zupreem Feline diet, and a dog chow mix we have attempted to add variety and improve the nutrition of their diet. In addition to the above, we now feed hard-boiled egg, blueberries, tomato, cantaloupe, canned pineapple, rinsed canned fruit cocktail, canned mixed vegetables, English peas, and raw corn on the cob. The corn seems to be a particular favorite of the adult cockatoos. Finally, this entire diet is sprinkled with a vionate vitamin, bonemeal mix. We feel that this diet goes a long way towards meeting their nutritional needs as well as providing an in - teresting , varied, and stimulating meal for the birds. In other words, its an attempt to meet both their physiological
and psychological needs.
The diet used in handraising the chick was also fairly complex. This diet was that suggested by Ann Nothaft in her book "Breeding Cockatoos." It consisted of a mix containing two (2) cups of high protein baby cereal, one (1) cup of
ground high protein dog chow, one (1) cup of yellow corn meal, one ( 1) cup of hulled sunflower seed, one (1) cup of hulled millet seed, and one (1) cup of raw wheat germ.