Grue brolga

Identification

The brolga is a tall bird with a large beak, a long and slender neck, and stilt-like legs. The sexes are indistinguishable in appearance, though females are usually a little smaller. The adult has a grey-green, skin-covered crown, and the face, cheeks, and throat pouch are also featherless and are coral red. Other parts of the head are olive green and clothed in dark bristles. The gular pouch, which is particularly pendulous in adult males, is covered with such dense bristles as to make it appear black. The beak is greyish-green in adult birds, long and slender, and the irises are yellowish-orange. The ear coverts appear as a grey patch of small feathers surrounded by red naked skin and the body plumage is silvery-grey. The feathers on the back and the wing coverts have pale margins. The primary wing feathers are black and the secondaries grey. The legs and feet are greyish-black. Juveniles lack the red band and have fully feathered heads with dark irises. A fully grown brolga can reach a height of 0.7 to 1.4 m (2 ft 4 in to 4 ft 7 in) and has a wingspan of 1.7 to 2.4 m (5 ft 7 in to 7 ft 10 in). Adult males have an average body mass of 6.8 kg (15 lb) with females averaging 5.66 kg (12.5 lb). The weight can range from 3.6 to 8.7 kg (7.9 to 19.2 lb). Heights up to 1.8 m (5 ft 11 in) in male brolga have been reported but presumably need confirmation. The brolga is the heaviest flying bird regularly found in mainland Australia, averaging slightly higher in body mass than other large resident species such as black swan, Australian pelican and the Australian race of sarus crane (Asian sarus cranes are heavier and significantly taller). Brolgas are as well as much heavier on average than the biggest flying land birds such as the very sexually-dimorphic Australian bustard and wedge-tailed eagle), although heavier birds such as wandering albatross may be seen as marine vagrants off the mainland. Brolgas probably rival black-necked storks and sarus cranes as the tallest flying birds in Australia.<p>The brolga can easily be confused with the sarus crane, but the latter's red head-colouring extends partly down the neck, while the brolga's is confined to the head. The brolga is more silvery-grey in colour than the sarus, the legs are blackish rather than pink, and the trumpeting and grating calls it makes are at a lower pitch. Additionally, in Australia, sarus crane distribution is limited to north-eastern areas, compared to the more widespread distribution of the brolga.

Taxonomie

When first described by the naturalist George Perry in 1810, the brolga was misclassified as a species of Ardea, the genus that includes the herons and egrets. It is, in fact, a member of the Gruiformes—the order that includes the crakes, rails, and cranes, and a member of the genus Antigone. Ornithologist John Gould used the name Grus australasianus when he wrote about it and noted it to be widespread in the north and east of Australia. He also recorded that it was easy to tame, and that James Macarthur had kept a pair at his home in Camden. Calling it the Australian crane, he mentioned that its early colonial name had been native companion. The Royal Australasian Ornithologists Union made brolga, a popular name derived from Gamilaraay burralga, the official name for the bird in 1926.<p>In 1976, it was suggested that the brolga, sarus crane (Antigone antigone), and white-naped crane (Antigone vipio) formed a natural group on the basis of similarities in their calls. This was further confirmed by molecular studies of their DNA. These also showed that the brolga is more closely related to the white-naped crane than it is to the morphologically more similar sarus crane.<p>The brolga was formerly placed in the genus Grus, but a molecular phylogenetic study published in 2010 found that the genus, as then defined, was polyphyletic. In the resulting rearrangement to create monophyletic genera, four species, including the brolga, were placed in the resurrected genus Antigone that had originally been erected by German naturalist Ludwig Reichenbach in 1853<p>Two subspecies were suspected to exist: A. r. argentea found in Western Australia, the Northern Territory and western Queensland and A. r. rubicunda, occurring in New Guinea, Queensland, New South Wales, Victoria, and South Australia. However, mitochondrial analyses have shown both populations sharing haplotypes indicating that they are a single taxon, though microsatellite markers show limited gene flow between the two populations.

Nom scientifique

Antigone rubicunda

Autorité

(Perry, 1810)

Ordre

Gruiformes

Famille

Gruidae

Genre

Antigone

Répartition et habitat

Brolgas are widespread and often abundant in north and north-east Australia, especially north-east Queensland, and are common as far south as Victoria. They are also found in southern New Guinea and as rare vagrants in New Zealand and the northern part of Western Australia. The population in northern Australia is estimated at between 20,000 and 100,000 birds and in southern Australia, 1,000 birds. The number of individuals in New Guinea is unknown. Until 1961, brolgas were thought to be the only species of crane in Australia, until the sarus crane was also located in Queensland.<p>Brolga movements in Australia are poorly understood, though seasonal flocks are observed in eastern Queensland in nonbreeding areas regularly, and a few coastal populations are suspected to move up to 500 km (310 mi) inland. Little is known of the movements and habitats of the New Guinea populations.<p>Further south, in Victoria and New South Wales, rainfall is spread more evenly throughout the year and the driest season lasts from December to May. At this time, southern populations congregate in inland flocking areas, which include upland marshes, the edges of reservoirs and lakes, pastures, and agricultural land. When rain arrives in June and July, they disperse to the coastal freshwater marshes, shallow lakes, wet meadows, and other wetlands where they breed. In south-west Victoria, breeding sites during and immediately after spring are freshwater wetlands, while freshwater, brackish and saline wetland sites are used for flocking during the autumn.<p>Queensland has the greatest numbers of brolgas, and sometimes flocks of over 1,000 individuals are seen. The bird is the official bird emblem for the state and also appears on its coat of arms. Breeding pairs and flocks are distributed across several floodplains along the Gulf of Carpentaria. Brolgas here preferentially use two grassland-dominated regional ecosystems (2.3.1 and 2.3.4), though over 30% of the cranes share four additional Eucalyptus-dominated woodland regional ecosystems with sarus cranes. Brolga numbers were highest in floodplains where grassland habitats dominated, and the largest flocks were also found in grassland habitats.

Migration

Espèce sédentaire

Comportement

Mode de migration: Espèce sédentaire.

Conservation

Tendance de la population: en déclin.

Tendance de la population

en déclin