The cockatiel (Nymphicus hollandicus), is a bird that is a member of the cockatoo family endemic to Australia. They are prized as household pets and companion parrots throughout the world and are relatively easy to breed. As a caged bird, cockatiels are second in popularity only to the budgerigar. The cockatiel is the only member of the genus Nymphicus. It was previously considered a crested parrot or small cockatoo; however, more recent molecular studies have assigned it to its own subfamily, Nymphicinae. It is, therefore, now classified as the smallest of the Cacatuidae (cockatoo family). Cockatiels are native to Australia, and favour the Australian wetlands, scrublands, and bush lands.
The cockatiel's distinctive erectile crest expresses the animal's emotional state. The crest is dramatically vertical when the cockatiel is startled or excited, gently oblique in its neutral or relaxed state, and flattened close to the head when the animal is angry or defensive. The crest is also held flat but protrudes outward in the back when the cockatiel is trying to appear alluring or flirtatious. In contrast to most cockatoos, the cockatiel has long tail feathers roughly making up half of its total length. At 30 to 33 cm (12 to 13 in), the cockatiel is the smallest of the cockatoos which are generally larger at between 30 and 60 cm (12 and 23.5 in). The "normal grey" or "wild-type" cockatiel's plumage is primarily grey with prominent white flashes on the outer edges of each wing. The face of the male is yellow or white, while the face of the female is primarily grey or light grey, and both sexes feature a round orange area on both ears, often referred to as "cheddar cheeks". This orange colouration is generally vibrant in adult males, and often quite muted in females. Visual sexing is often possible with this variant of the bird. Cockatiels are relatively vocal birds, the calls of the male being more varied than that of the female. Cockatiels can also be taught to sing specific melodies. Much like parrots, but not quite to that extent, Cockatiels can be taught to repeat words spoken by human owners.