Yellow-Tailed Black Cockatoo

## Description

The Yellow-tailed black cockatoo is a large cockatoo native to the forests of Australia. It has a short mobile crest on the top of its head, and the plumage is mostly brownish-black with paler feather margins in the neck, nape, and wings, and pale yellow bands in the tail feathers. The male has a black bill, a dull yellow patch behind each eye, and pinkish or reddish eye-rings. The female has grey eye-rings, a horn-colored bill, and brighter and more clearly defined yellow cheek patches. Immature birds have duller plumage overall, a horn-colored bill, and grey eye-rings.

## Appearance

The yellow-tailed black cockatoo is 55–65 cm (22–26 in) in length and 750–900 grams in weight. It has a short mobile crest on the top of its head, and the plumage is mostly brownish-black with paler feather-margins in the neck, nape, and wings, and pale yellow bands in the tail feathers. The tails of birds of subspecies funereus measure around 33 cm (13 in), with an average tail length 5 cm (2.0 in) longer than xanthanotus. Male funereus birds weigh on average around 731 g (1.612 lb) and females weigh about 800 g (1.8 lb). Birds of the xanthanotus race on the mainland average heavier than the Tasmanian birds; the males on the mainland weigh on average around 630 g and females 637 g (1.404 lb), while those on Tasmania average 583 and 585 g (1.290 lb) respectively. Both mainland and Tasmanian birds of the xanthanotus race average about 28 cm (11 in) in tail length. The plumage is a more solid brown-black in the eastern subspecies, while the southern race has more pronounced yellow scalloping on the underparts.

The male yellow-tailed black cockatoo has a black bill, a dull yellow patch behind each eye, and pinkish or reddish eye-rings. The female has grey eye-rings, a horn-coloured bill, and brighter and more clearly defined yellow cheek-patches. Immature birds have duller plumage overall, a horn-coloured bill, and grey eye-rings; The upper beak of the immature male darkens to black by two years of age, commencing at the base of the bill and spreading over ten weeks. The lower beak blackens later by four years of age. The elongated bill has a pointed maxilla (upper beak), suited to digging out grubs from tree branches and trunks. Records of the timing of the eye ring changing from grey to pink in male birds are sparse, but have been recorded anywhere from one to four years of age. Australian farmer and amateur ornithologist John Courtney proposed that the similarity between juvenile and female eye rings prevented adult males becoming aggressive to younger birds. He also observed the eye rings to flush brighter in aggressive males. Moulting appears to take place in stages over the course of a year, and is poorly understood.

The yellow-tailed black cockatoo is distinguished from other dark-plumaged birds by its yellow tail and ear markings, and its contact call. Parts of its range overlap with the ranges of two cockatoo species that have red tail banding, the red-tailed cockatoo and the glossy black cockatoo. Crow species may appear similar when seen flying at a distance; however, crows have shorter tails, a quicker wing beat, and different calls.

An all-yellow bird lacking black pigment was recorded in Wauchope, New South Wales, in December 1996, and it remained part of the local group of cockatoos for four years. Birds with part-yellow plumage have been recorded from different areas in Victoria.

## Distribution

Yellow-tailed black cockatoos are found over southeastern Australia including the island of Tasmania and the islands of the Bass Strait (King, Flinders, Cape Barren islands), and also on Kangaroo Island. A tiny population inhabits the Eyre Peninsula. There they are found in sugar gum woodland in the lower peninsula and move to the mallee areas in the northern peninsula after breeding. There is evidence that birds on the New South Wales south coast move from elevated areas to lower-lying areas towards the coast in winter. Yellow-tailed black cockatoos prefer to live in forests, while also occur in pine plantations, and occasionally in urban areas, as long as there is a plentiful food supply. They have also spread to parts of suburban Sydney, particularly on or near golf courses, pine plantations, and parks, such as Centennial Park in the eastern suburbs.

## Behavior

Yellow-tailed black cockatoos are diurnal, raucous, and noisy birds that are often heard before being seen. They make long journeys by flying at a considerable height while calling to each other, and they are often seen flying high overhead in pairs, or trios comprising a pair and their young, or small groups. Outside of the breeding season in autumn or winter, they may form flocks of a hundred birds or more, while family interactions between pairs or trios are maintained. They are generally wary birds, although they can be less shy in urban and suburban areas. They generally keep to trees, only coming to ground level to inspect fallen pine or Banksia cones or to drink. The flight of these cockatoos is fluid and has been described as "lazy", with deep, slow wingbeats. They like to roost in tall eucalypts emergent over other trees in wooded areas. Here they rest for the night and also rest to shelter from the heat of the day. Yellow-tailed black cockatoos often socialize before dusk, engaging in preening, feeding young, and flying acrobatically. If the weather is bad, flocks will return to roost earlier. The usual contact call of these birds is a high-pitched wailing call, ‘kee-ow … kee-ow … kee-ow’, made while flying or roosting, and can be heard from afar. They may also make a harsh screeching alarm call and a soft, chuckling call when searching for cossid moth larvae. Adults are normally quiet when feeding, while juveniles make frequent noisy begging calls.

## Diet

Yellow-tailed black cockatoos are omnivores and have varied diets. They eat mainly seeds of native trees, particularly she-oaks, but also Eucalyptus, Acacia, Banksia, and Hakea species. Nectar is also included in the diet such as that from native shrubs. They are also very fond of the larvae of tree-boring beetles.

## Reproduction

Yellow-tailed black cockatoos are monogamous and form pairs. Their breeding season varies according to latitude, taking place from April to July in Queensland, January to May in northern New South Wales, December to February in southern New South Wales, and October to February in Victoria, South Australia, and Tasmania. During this time the male attracts the female by puffing up his crest and spreading his tail feathers to display his yellow plumage. Softly growling, he approaches the female and bows to her three or four times. His eye ring may also flush a deeper pink. Pairs then nest in large vertical tree hollows of tall trees, generally eucalypts, which may be living or dead. They like to use the same tree may for many years. Hollows can be 1 to 2 meters (3.3 to 6.6 ft) deep and 0.25-0.5 meters (9.8-19.7 in) wide, with a base of woodchips. Both the male and female prepare the hollow for breeding, which involves peeling or scraping off wood shavings from the inside of the hollow to prepare bedding for the eggs. The female then lay a clutch of 1-2 white lustreless rounded oval eggs which may have the occasional lime nodule. The female incubates the eggs alone and begins after the completion of laying. She enters the hollow feet first and is visited by the male who brings food two to four times a day. Later both parents help to raise the chicks. Newly hatched chicks are covered with yellow down and have pink beaks that fade to a greyish-white by the time of fledging. The young fledge from the nest 3 months after hatching and remain in the company of their parents until the next breeding season.

## Population

### Population threats

Yellow-tailed black cockatoos are not threatened at present, however, fragmentation of habitat and loss of large trees suitable for nesting has caused a population decline in Victoria and South Australia. Furthermore, these birds may lose most of their mainland range due to climate change.

### Population number

According to IUCN Red List, the total population size of the Yellow-tailed black cockatoo is around 25,000 individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.

## References

https://animalia.bio/yellow-tailed-black-cockatoo