Cockatoo

Cockatoos are a group of 22 parrot species that make up the family Cacatuidae, the sole family within the superfamily Cacatuoidea. They are native to Australasia, with a range stretching from the Philippines and the eastern Indonesian islands of Wallacea through New Guinea and the Solomon Islands to Australia. Alongside the true parrots (Psittacoidea), they belong to the order Psittaciformes.

These birds are easily recognized by their showy crests and hooked bills. Their feathers are usually less vivid than those of other parrots, often white, grey, or black, with splashes of color on the crest, cheeks, or tail. On the whole, they are larger than most parrots, though the cockatiel—the smallest cockatoo—is medium-sized. The cockatiel’s exact place in the family tree is still debated, but it is known to be one of the earliest branches off the cockatoo lineage. The remaining species fall into two main groups. One branch consists of the five large, black cockatoos in the genus *Calyptorhynchus*. The other, larger branch includes the genus *Cacatua*, which holds 12 white-plumaged species, plus three single-species genera that split off earlier: the pink-and-grey galah, the mostly grey gang-gang cockatoo, and the large, black-plumaged palm cockatoo.

Cockatoos feed mainly on seeds, tubers, corms, fruit, flowers, and insects. They often gather in large flocks, especially when feeding on the ground. They are monogamous and nest in tree hollows. Habitat loss, particularly the clearing of old, large trees that provide nesting sites, has harmed some species. Others, however, have adapted well to human-altered landscapes and are considered agricultural pests.

In aviculture, cockatoos are popular but challenging to keep. The cockatiel is the easiest to care for and by far the most common in captivity. White cockatoos are more often kept than black ones. The illegal trade in wild-caught birds is a threat to several species in the wild.

The word "cockatoo" entered English in the 1600s, coming from the Dutch *kaketoe*, which itself came from the Malay *kakatua*. Early spellings included cacato, cockatoon, crockadore, cokato, cocatore, and cocatoo. These forms also gave rise to the family and genus names Cacatuidae and *Cacatua*. In Australian slang, a lookout for illegal activities, especially gambling, is called a "cockatoo." Small-scale farmers are sometimes humorously or dismissively referred to as "cocky farmers."

The cockatoos were first classified as a subfamily, Cacatuinae, within the parrot family Psittacidae by English naturalist George Robert Gray in 1840, with *Cacatua* as the type genus. Since then, authorities have treated them as either a full family or a subfamily. Molecular studies show that the earliest split from the ancestral parrots were the New Zealand parrots (Strigopidae), followed by the cockatoos, which form a distinct clade. The remaining parrots then spread across the Southern Hemisphere, diversifying into the many species of true parrots (Psittacoidea).

The relationships among cockatoo genera are mostly settled, though the cockatiel’s position at the base of the group is still uncertain. It may be the most primitive of all cockatoos, the sister to the black cockatoos (*Calyptorhynchus*), or the sister to a clade that includes the white and pink cockatoos plus the palm cockatoo. The other species fall into two main clades: one with the black *Calyptorhynchus* species, and another containing the rest. Most authorities place the black palm cockatoo (*Probosciger*), the galah (*Eolophus*), and the gang-gang cockatoo (*Callocephalon*) in this second clade, though *Probosciger* is sometimes considered the most basal of all cockatoos. The remaining species are mostly white or slightly pinkish and belong to the genus *Cacatua*. The genera *Eolophus* and *Cacatua* are hypomelanistic. *Cacatua* is further split into the subgenera *Licmetis* (corellas) and *Cacatua* (white cockatoos), though "white cockatoo" is also used for the whole genus. The five *Calyptorhynchus* species are called black cockatoos and are divided into two subgenera: *Calyptorhynchus* and *Zanda*. The former group shows sexual dichromatism, with females having heavily barred plumage, and the two subgenera also differ in the begging calls of their young.

The cockatoo fossil record is sparse. The only truly ancient fossil is a species of *Cacatua* (likely subgenus *Licmetis*) from Early Miocene deposits (16–23 million years ago) at Riversleigh, Australia. Though fragmentary, it resembles the western corella and the galah. In Melanesia, subfossil bones of *Cacatua* species that apparently died out after early human settlement have been found on New Caledonia and New Ireland. These fossils offer only limited insight into cockatoo evolution and relationships.