There are many different varieties of the Australian cockatoo –the pink cockatoo, the black, the white, red or yellow tailed and many more. The most famous is the sulphur crested cockatoo. They are a large white parrot with a forward-curving yellow crest on their head which they raise for great effect. They have a powerful beak and a raucous cry, and after the breeding season usually gather in large flocks where food is plentiful. They have a “sentinel warning system”. When feeding on the ground, a few birds perch in trees and screech loudly at signs of intruders, when the entire flock will immediately rise into the air.