katoos maintain their plumage with frequent preening throughout the day. They remove dirt and oil and realign feather barbs by nibbling their feathers.

They also preen other birds' feathers that are otherwise hard to get at. Cockatoos produce preen-oil from a gland on their lower back and apply

it by wiping their plumage with their heads or already oiled feathers. Powder-down is produced by specialised feathers in the lumbar region and distributed by the preening cockatoo all over the plumage.

Moulting is very slow and complex. Black cockatoos appear to replace their flight feathers one at a time, their moult taking two years to complete. This process is much shorter in other species, such as the galah and long-billed corella, which each take around six months to replace all their flight feathers. Voice The vocalisations of cockatoos are loud and harsh. They serve a number of functions, including allowing individuals to recognize one another, alerting others of predators, indicating individual moods, maintaining the cohesion of a flock and as warnings when defending nests. The use of calls and number of specific calls varies by species; the Carnaby's black cockatoo has as many as 15 types of call, whereas others, such as the pink cockatoo, have fewer. Some, like the gang-gang cockatoo, are comparatively quiet but do have softer growling calls when feeding. In addition to vocalisations, palm cockatoos communicate over large distances by drumming on a dead branch with a stick. Cockatoo species also make a characteristic hissing sound when threatened. Distribution and habitat A mainly white cockatoo with a few pale-pink feathers on its face. The cockatoo is perched on a branch in a tree standing on its right foot while holding what appears to be a rambutan fruit up to its open beak with its left foot The Tanimbar corella is restricted to the islands of Tanimbar in Indonesia; a few feral escapees are found in Singapore. Cockatoos have a much more restricted range than the true parrots, occurring naturally only in Australia, Indonesia, the Philippines, and some Pacific regions. Eleven of th