The cockatoo is any one of around twenty species of bird1, and is a member of the parrot family. In general, cockatoos are larger than other parrots, though they have the characteristic curved beak and a zygodactyl foot, that is one which has two toes pointing forwards and two backwards. They have a beautiful headcrest which can be raised or lowered at will, but their plumage in general is not as showy as that of other parrots - the beautiful, iridescent feathers of other species is lacking from the cockatoo family.
Like the budgerigar, cockatoos are found natively in Australia and nearby islands, though they make popular household pets in various locations around the world. Because Australia prudently forbids the export of native wildlife, all pet cockatoos are bred in captivity. A hand-reared cockatoo is docile, intelligent and enjoys interaction with its owner, though the time, expense and effort involved in correctly caring for a cockatoo is daunting, and certainly something to be researched carefully before making a purchase.
For many years, the distinction between the cockatoo and cockatiel has been unclear. Cockatiels are a small type of cockatoo with a distinctive, yellow crest. Smaller, and more slender, cockatiels have recently been genetically confirmed as a member of the family Cacatuinae2 and are related to the black cockatoo and white cockatoo.
1: These species all belong to the family Cacatuinae. This family is one of the two which make up the order Psittaciformes, which includes all parrots.
2: The cockatiel is named Nymphicus hollandicus, which reflects the circumstances of their discovery by a group of Dutch travellers who were so taken by their beauty that they compared them to the nymphs of mythology.