It is not easy for a single species to stand out among a group of birds as spectacular as the cockatoos, but the striking palm cockatoo does so quite handily. At nearly 30 inches in length and with a 30-inch wingspan, this giant among cockatoos approaches the hyacinth macaw, Andorhynchus hyacinthus, the largest of the world’s 350+ species of parrot-like birds, in size. Its jet black feathers are set off by powdery gray down and highlighted by brilliant red cheek patches. Adding to the air of imposing size, the head is topped by a crest of long feathers and the beak is massive. Today I would like to tell you about my involvement with the first large group of palm cockatoos brought into this country and to discuss some of this magnificent creature’s unique characteristics.
But first, if I may, a bit more about what distinguishes this bird from the approximately 20 other species belonging to the family Cacatuidae, the cockatoos (all of which are members of the order Psittaciformes, along with parrots, lories and macaws). Palm cockatoos, also known as black palm cockatoos or goliath aratoos, are the only tropical rain forest-adapted members of their family -- the rest being more at home in dry, often sparsely vegetative habitats. They are native to northern Australia’s Cape York Peninsula New Guinea, Aru Island and smaller neighboring islands. Three subspecies have been identified, with New Guinea's P. a. goliath being the largest.
Although this bird is unique among cockatoos in many ways, perhaps its most distinguishing feature is tool use -- a phenomenon quite rare among birds in general. Most likely as an adaptation to a thickly forested habitat where sound travels poorly, palm cockatoos beat sticks and large nuts against hollow trees when communicating with others of their kind. This behavior, known as “drumming”, is repeated anywhere from 2 to over 100 times, and creates quite a racket. In fact, “palms” seem prone to odd modes of self-expression -- when frightened, rather than hissing in typical cockatoo fashion, they stamp their feet!
Palm cockatoos are also unusual in possessing bare patches on the cheeks. The skin on these patches varies in color from dull red to bright crimson, depending on the bird’s mood, stress level, health and other factors of which we are as yet unaware. The face patch can also be covered with feathers during communication displays. The maxillary, or upper beak, is twice the size of that of its largest relative (its genus name, Probosciger, alludes to the beak). Extraordinarily powerful, this impressive structure assists the bird in securing its diet of large nuts (in captivity, even Brazil nuts pose no problem), seeds, fruits and leaf buds. The lower beak meets the upper only at the tip, leaving the mouth always slightly open. Unlike other cockatoos, which forage in large flocks, “palms” feed singly, in pairs, or in groups of up to 7 in number. Pairs return to their territories in the evening, but roost separately.
Breeding and Nesting
In reproductive biology as well, the palm cockatoo breaks with its close relatives. The male’s breeding display is the group’s most complex – flying high above the ground towards his mate, he raises his spectacular crest, deepens his cheek patch color, and calls loudly. They are the only cockatoos to build stick nests within their nest cavities – perhaps as a precaution against flooding - and their young are unique in hatching without down and in having such a long (to 160 days) nestling period. Even after all that time, young palm cockatoos fly poorly upon leaving the nest and are fed by their parents for an additional 6 weeks.
Strictly protected by the governments of New Guinea and Australia (and listed on Appendix I of CITES, The Committee on International Trade in Endangered Species), palm cockatoos were relatively unknown in American aviculture until quite recently. In fact, zoos here did not pay much attention to Psittacines in general – intelligent and gregarious, they need lots of room, stimulation and appropriate social groups and thus are difficult to provide for. After observing flocks of military macaws, Asa militaris, and other species, in the wild, I came to regard parrots and their relatives, in terms of their captive needs, as the “primates of the bird world”. Those of you who keep them as pets are no doubt familiar with their curiosity, and are fortunate in having a wide range of helpful products from which to choose when looking to keep them happy.
In 1983 the US Fish and Wildlife Service confiscated a large group of palm cockatoos, and placed them with various zoos and qualified private individuals. I was working in the Bronx Zoo’s bird department at the time, and learned that I would be assisting in the hand rearing of two chicks. Given the rarity of this species in captivity, I was excited by the opportunity to perhaps contribute to our understanding of its captive husbandry. The group eventually did quite well, and gave rise to a good percentage of the individuals in this country today.
The two chicks were at first fed (via syringe) around the clock, and thus required attention at all hours of the night. This quickly gave rise to their names – “OT” and “MOT”, signifying “Overtime” and “More Overtime”! Their helplessness (and the fattened pay checks they engendered) endeared the birds to their keepers. With barely any down feathers, they were at first kept at quite warm temperatures (92 F or so) in an incubator. Feather growth increased from age 3 weeks, when the temperature was reduced to 85F, and was complete when the birds were approximately 3 months old. The chicks’ face-patch color was variable even during their first weeks of life, although I cannot say what the changes meant. In common with most healthy nestlings, their feeding reaction was quite strong and, oddly, accompanied by much head bobbing.
In those days, formulas for hand-rearing cockatoos were not standardized, and the various zoos involved in the project experimented quite a bit. A dilute mix of Pedialite, monkey chow, baby cereal and fruit was common to most diets, and worked well (although not without some digestive upset). Today, both zoos and hobbyists have a number of fine products available, and hand-rearing success stories are more common. The chicks began pecking at solid food at 2 ½ - 3 months of age – I later learned that the timing of this milestones varies greatly among palm cockatoo chicks. Supplemental formula was given until the birds were approximately 4 months old and gaining weight consistently. They were later transferred to the World of Birds building, where their exhibit remains a major attraction.
I am happy to say that we learned quite a bit that has been of use to other bird keepers, hobbyists and their charges, and helped establish this magnificent species soundly in North American zoos and private collections.
About the Author
For more articles by Frank Indiviglio visit That Avian Blog.