The relationship of these birds to the breeding pair is unknown. Breeding pairs defend the nest hole, though other cockatoos may remain nearby during the nesting period. The nest is lined with wood chips chiselled from the walls of the nest cavity. The 1-2 eggs are laid in a nest cavity, which the adults enlarge from naturally occurring holes in trees. Nest exploration may occur at any time of year, with greatest activity at the nest occurring between July and December. Sulphur-crested cockatoos are monogamous, forming long-lasting pair bonds. Their potential to impact on native species is minor due to their largely agricultural and ground feeding habit, and the absence of kaka in the fragmented forest patches they occupy. In native forest their impact is minimal, though they can have a massive impact on individual trees, at times stripping large numbers of branches. They may also cause damage to pine plantations, stripping branches when feeding. Otherwise they are more of a nuisance value for rural communities, feeding on walnuts and damaging ornamental conifers. Their impact on agriculture is generally localised, with flocks targeting specific fields of maize on a few properties just after sowing and when mature. Sulphur-crested cockatoos mainly eat the seeds from introduced conifer trees and pasture and crop species, such as grasses and maize. Each year many chicks are taken from nests, and occasionally large numbers of adults are trapped. Populations are kept in check by capture for the pet trade. Remaining New Zealand populations each contain fewer than 100 birds. The largest populations, Port Waikato, and Turakina and Pohangina Valleys, contain several hundred birds. Sulphur-crested cockatoos are uncommon and localised. The largest populations are associated with arable land, especially where maize is grown near to woodland habitat. Sulphur-crested cockatoos are mainly found in farmland close to native forest or woodland and exotic tree plantations. They are wide-ranging and may be seen outside these core areas, though isolated birds may be free-ranging pets or cage-escapes. There are also small populations in the Waitakere ranges and at Wainuiomata, and on Banks Peninsula and the Catlins in the South Island. The largest populations are south of Port Waikato, and the Turakina and Pohangina Valleys. In New Zealand most populations are on the west coast of the North Island, though some are spreading east into the Bay of Plenty, Hawke’s Bay and Wairarapa. Populations have been established outside this range, including Western Australia and New Zealand. Other subspecies are found throughout New Guinea and the Papuan Islands. Sulphur-crested cockatoos are widespread in northern and eastern Australia where woodland habitat is present. Similar species: sulphur-crested cockatoos are not easily confused with other New Zealand species, but flocks on the ground or in flight may be confused with cattle egrets from a distance. They also make softer cries, and guttural croaks or barks during conflict. Voice: the most common call is a harsh screech given in flight, when perched and when alarmed. Sulphur-crested cockatoos usually occur as pairs or small groups in spring and summer, may form large flocks in autumn and winter. Juveniles have a paler eye, and may have some grey in their plumage. The black beak is robust, capable of breaking into hard seed pods and cones. Remaining plumage is white, with pale yellow on the underside of the tail and wing. The forward curving crest is normally laid back, but fans out when aroused. Sulphur-crested cockatoos are large, stocky cockatoos, with short broad wings and a prominent yellow crest.

In winter, flocks of hundreds of birds may form to feed on crops, such as maize. Birds occasionally venture into residential areas. They are typically found in lowland hill country farmland, with a mixture of exotic and native forest and arable land use.

The area over which they occur has increased over time, though their numbers are not great this species suffering considerable persecution, particularly through live-capture for the pet trade. Sulphur-crested cockatoos were introduced to New Zealand in the late 19th Century and soon established wild populations. They are localised in their New Zealand distribution, with most populations on the west coast of the North Island, though flocks also occur on Banks Peninsula and the Catlins in the South Island. Sulphur-crested cockatoos are large white parrots, with yellow crest feathers, and yellow suffusion on the underside of the tail and wing.

Yellow and white cockatoo