Chapter I
General Characteristics and Natural History
by Mike Taylor (Editor) from the White Oak Conservation Center
In an attempt to present the information in this husbandry manual in a more organized and more easily accessable format, the information for this section has been extracted from the following chapters;
Housing by Sherry Branch and Ron Young
Behavior by Pat Rider and Mike Taylor
Reproduction by Trent Swigert
Adult Nutrition by Carla Marquardt and Dr. Kimberly Howard.
Adult Medical Care by Dr. Bond, Diane Downs and Sharon Wolf
Physical Characteristics.
Palm cockatoos, while similar to other cockatoos in some ways, have their own unique physical characteristics. They are considered by many to be the largest of the cockatoos (Lint, 1976; Low, 1980; Forshaw 1981), ranging from 49 cm to 68 cm in total length, measured from the top of the head to the tip of the tail. The palm cockatoo is a long, lean bird, and is relatively lightweight for its size.
There is a wide range of size among individual birds and across subspecies. At the Avicultural Breeding and Research Center (ABRC), females have ranged in weight from 503 to 950 gm and the males from 545 to 1092 gm.
Perhaps the most distinctive features of the palm cockatoo are the red, naked facial patches. Facial color in these birds may be related to several factors including stress level, general health, and their environment. Thus, the tone of the facial patches is not constant and may range from a brilliant crimson to almost white to a dull, blotchy burgundy. The bare skin may be hidden by the coverlet feathers, a further indicator of the bird's attitude.
A healthy palm cockatoo has powder down, but in a lesser amount than the white cockatoo species. The powder dulls the glossy beak and lends a subtle grey color to their black plumage. Feathering is sparse on the palm cockatoos’ black legs.
Palm cockatoo beaks are unique in their size and structure. The maxilla, or upper beak, is almost twice the size of a Moluccan cockatoo's (Cacatua moluccensis). The beak has great strength for cracking large nuts, but the maxilla is almost hollow in the area below the cere, making it vulnerable to physical trauma. The maxilla has a large biting surface on the underside that opposes the biting edge of the mandible. The mouth is never completely closed because of the structure of the maxilla and mandible. The structure of the mouth is also different than other cockatoos in that the glottis is deep-seated.
Habitat.
Most cockatoo species are adapted to dry climates and associated vegetation. The exception is the palm cockatoo, which is adapted to tropical rainforest habitats (Forshaw, 1981; Alderton, 1983; Deifenbach, 1985; Smith, 1987). Their recent evolution has taken place in a wetter, warmer climate under very different selective forces than those experienced by other cockatoos (Smith, 1987). They, therefore, have developed many different social, behavioral, and physical traits, which enable them to compete in their rainforest environment.
Social Organization.
Unlike other cockatoos, palm cockatoos are not flock feeders. They are generally observed singly, in pairs, or in small groups of up to five or seven individuals (Forshaw, 1981; Deifenbach, 1985). It is unknown if these small groups are made up of related or unrelated individuals. Palm cockatoos roost separately, but begin calling to each other after sunrise (Forshaw, 1981). Small groups congregate on trees in neutral areas during the day, where they preen, perform displays, and engage in various other social interactions (Eastman & Hunt, 1966; Forshaw, 1981; Wood, 1988). Pairs separate from these parties at sunset and return to their own territories. After making a round of sites within their territory, they return to roost, separately, in the same tree (Wood, 1988).
Pairs maintain territories that include several potential nest trees. They regularly visit these sites throughout the year with increasing frequency during the breeding season (Wood, 1988). The palm cockatoo's breeding season in the wild has been observed as being prolonged, and may vary in accordance with climatic conditions (Forshaw, 1981), usually occurring during the months of August through January. They inspect the nest trees, sometimes adding splintered twigs as nest material, perform displays, and defend their territories from intruders (Wood, 1988). Nest building and maintenance, and territorial defense may be very important to maintaining the "pair bond".
Breeding cavities are usually found at considerable heights and are often more than 1 meter deep with a diameter of 25 to 60 cm (Forshaw, 1981). Once the pair accepts a nest site, they will usually use it year after year (Deifenbach, 1985). After the female lays a single egg, it is incubated by both parents for about 30 days. It takes three to four days for the chick to hatch after pipping. The hatched chick is totally naked and does not develop down, unlike all other cockatoo chicks which are hisuated (Silva, 1991). In the wild, the chick is believed to be brooded primarily by the female. The chick does not emerge from the nest for 100 to 110 days, the longest nestling period known for any parrot species. For about two weeks after leaving the nest, the chick is not fully competent to fly and continues to be fed by its parents for an additional six weeks (Forshaw, 1981; Deifenbach, 1985).
Palm cockatoos are long lived, highly specialized feeders with a slow reproductive rate. As with other large birds inhabiting tropical rainforests, they appear to have a stable population where recruiting younger individuals is normally difficult.
Status in the Wild.
There have not been many recent surveys concerning the palm cockatoos status in the wild. The only concrete indication of their status comes from the population found on Cape York Peninsula, Queensland, Australia. It has been found that this population is decreasing (Bruning, 1996). Prior to this disturbing report, this population was believed to have been stable. A research project to determine the cause of this decline is being spearheaded by Dr. Don Bruning of Wildlife Conservation International/Bronx Zoo and Joe Forshaw.
Diet in the Wild.
Researchers report that palm cockatoos have been observed feeding on seed, nuts, fruits, berries, and leaf buds. They are primarily arboreal feeders, but have been seen on the ground feeding on seeds and fallen fruit. According to Forshaw (1978), they were observed on the Cape York Peninsula eating seeds of the kanari tree (Canarium australasicum) and the black bean tree (Castanospermum australe), and the fruits of the nonda tree (Parinarium nonda) and Pandanus sp. They have been observed eating seeds which have passed through cassowaries, possibly making them easier to open or concentrated into one area. Cassowaries have also been seen eating fruit which has been discarded by foraging palm cockatoos (D.Bruning, pers. comm.).
