Австралиялық ақ қасқыр құсы

Species of bird
the Australian white ibis

The Australian white ibis (Threskiornis molucca) is a wading bird of the ibis family, Threskiornithidae. It is widespread across much of Australia. It has a predominantly white plumage with a bare, black head, long downcurved bill, and black legs. While it is closely related to the African sacred ibis, the Australian white ibis is a native Australian bird. Contrary to urban myth, it is not a feral species introduced to Australia by people, and it does not come from Egypt. Populations have disappeared from natural breeding areas such as the Macquarie Marshes in northern New South Wales. Management plans have been introduced to control problematic urban populations in Sydney. Due to its increasing presence in the urban environment and its habit of rummaging in garbage, the species has acquired a variety of colloquial names such as "tip turkey" and in recent years has become an icon of Australia's popular culture, regarded with glee by some and passionate revulsion by others.

It was initially described by Georges Cuvier in 1829 as Ibis molucca. It is considered part of a superspecies complex with the sacred ibis (T. aethiopicus) of Africa, and the black headed ibis (T. melanocephalus) of Asia. Its status in the complex has vacillated over the years. Many older guidebooks referred to the bird as a species, T. molucca, until a comprehensive review of plumage patterns by Holyoak in 1970. Holyoak noted the three species' similarities and that the Australian taxon resembled T. aethiopicus in adult plumage and T. melanocephalus in juvenile plumage. He proposed that they all be considered part of a single species, T. aethiopicus. This was generally accepted by the scientific community until Lowe and Richards's assessment of plumage in 1991. They again recommended the recognition of molucca at species level. This was followed by a chromosome study, which highlighted each of the three species having a different karyotype. The Australian white ibis has been considered a full species by most authorities since then.

The Australian white ibis is a fairly large ibis species, around long and has a bald black head and neck and a long black downcurved beak, measuring over in the male, and under in the female. There is some sexual dimorphism in size, as the slightly heavier male weighs compared to the female. As a comparison, the American white ibis generally attains in weight. The body plumage is white, although it may become brown stained. Inner secondary plumes are displayed as lacy black "tail" feathers. The upper tail becomes yellow when the bird is breeding. The legs and feet are dark and red skin is visible on the underside of the wing. Immature birds have shorter bills. The head and neck are feathered in juveniles. The call is a long croak. The Macquarie Marshes in north western New South Wales used to be one of the main breeding areas of the bird, with 11,000 nests reported in 1998. However, since 2000, none have been reported breeding there.

The species has been able to colonise urban areas by reducing its fear response when in close proximity to humans, and by significantly widening its suite of food items to include human refuse – strategies that other closely related species such as the straw necked ibis and the spoonbills have not replicated. Questions surrounding the origins of recent highly urbanised and closely human habituated populations of the species are complicated by the establishment of free flying exhibit flocks of formerly captive birds at a number of zoos and wildlife parks, including Sydney's Taronga Zoo, which first acquired birds for this purpose around 1971. The resident Taronga flock nested in exotic Canary Island date palms, and was notably very closely habituated to people; approaching them at close quarters, feeding from rubbish bins and scavenging food from outdoor dining areas. These previously undocumented behaviours became closely associated with the urban Sydney flocks that emerged from around 1980 onwards, directly across the harbour in the Royal Botanic Gardens and the Sydney CBD, and further afield in the Centennial Parklands. The first big colony set up in the Sydney suburb of Bankstown and started to cause anxiety in the local community. It is estimated the colony was the largest outside the Macquarie Marshes, their natural breeding wetland in inland NSW. The birds have also come to be regarded as a problem species in Victoria as a result of their scavenging activities, scattering rubbish from tips and bins in the process, and earning the widespread nickname "bin chicken". They are even known to snatch sandwiches from picnickers. Such behaviour, together with their propensity to build nests in "inappropriate" places, and competition with captive animals, led to surplus birds being relocated from Healesville Sanctuary to Sale. However, the birds returned in a few days. They are a protected species in Queensland, New South Wales and Victoria.

The Australian white ibis' range of food includes both terrestrial and aquatic invertebrates and human scraps. The most favoured foods are crayfish and mussels, which the bird obtains by digging with its long bill. Ibises have also been observed to eat cane toads by "flicking" them about to make them secrete their defensive toxin, then washing the toad in a nearby water source before consuming it. Researchers called this a learned behaviour "observed in multiple different regions". Although scientists do not think that the toxin affects most birds, they believe birds avoid it because of its "awful" taste.

Breeding season varies with the location within Australia, generally August to November in the south, and February to May, after the wet season, in the north. The nest is a shallow dish shaped platform of sticks, grasses or reeds, located in trees, generally near a body of water such as a river, swamp or lake. Ibises commonly nest near other waterbirds such as egrets, herons, spoonbills or cormorants. Two to three dull white eggs are laid measuring The clutch is then incubated for 21–23 days. Hatchlings are altricial, that is, they are naked and helpless at birth, and take 48 days to fledge.

The ibis is fairly common and is seen in groups of up to 30 birds along roads, on beaches and in the forest. It also visits villages where it forages with the domestic chickens. It feeds on the ground on invertebrates. When breeding, it nests in small colonies in forest trees and on islands in Lake Tegano.

The ibis has become a popular symbol of Australian identity, and has been depicted on television, in art, and in online memes. In March 2021, the Macquarie Dictionary blog chose "bin chicken" as an Australian word of the week, and wrote that it was potentially "competing with the kangaroo for the position of most iconic Australian animal". In 1989, the Municipality of Hunter's Hill on Sydney Harbour adopted a coat of arms granted by the College of Arms which featured two ibis birds as supporters. In December 2017, the ibis placed second in Guardian Australia inaugural Bird of the Year poll, a nationwide competition for Australia's favourite native bird. The ibis led the poll for much of the voting, but lost to the magpie by 843 votes (19,926 votes to 19,083). In April 2022, Queensland sports minister Stirling Hinchliffe suggested the ibis as a potential mascot for the 2032 Olympic Games which are scheduled to be held in Brisbane.