| Australian bustard | |
|---|---|
 | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Otidiformes |
| Family: | Otididae |
| Genus: | Ardeotis |
| Species: | A. australis |
The Australian Bustard (Ardeotis australis) is a large ground-dwelling bird that is common in grassland, woodland and open agricultural country across northern Australia and southern New Guinea. It stands at about one metre (3 ft 3 in) high, and its wingspan is around twice that length. The species is nomadic, flying to areas when food becomes plentiful, and capable of travelling long distances. They were once widespread and common to the open plains of Australia, but became rare in regions that have been used for farming. The bustard is omnivorous, mostly consuming the fruit or seed of plants, but also eating invertebrates such as crickets, grasshoppers, smaller mammals, birds and reptiles.
The species is also commonly referred to as the plains turkey, and in Central Australia as the bush turkey, particularly by Aboriginal people, who hunt it, although the latter name may also be used for the Australian brushturkey, as well as the orange-footed scrubfowl.
Description[]
The only Australian species of Ardeotis, a genus occurring in the African, Indian and Australasian regions, this bustard is a large terrestrial bird that resembles an American turkey in its form and behaviour. It is readily distinguished by its large size, long legs and habits while slowly striding across open plains. The general coloration of A. australis is black at the crown and nape, the long neck is pale grey at the front, and brown plumage cover the wings and upper body. The sexes are similar in appearance, females are smaller in stature, wingspan and weight than the males. The abdomen is white and separated from the light grey of the neck by a black band of feathers. The wing coverts are patchily coloured with black and white patterning, which is visible while at rest or especially in flight. The iris is white, and their beak is variously whitish to brown in colour. The legs are long and yellow to cream coloured. Males are up to 1.2 m (47 in) tall with a 2.3 m (7.5 ft) wingspan. The average weight for males is 6.3 kg (14 lb), with a range of 4.3 to 12.76 kg (9.5 to 28.1 lb). The female is quite a bit smaller at 80 cm (31 in) tall, with a 1.8 m (5.9 ft) wingspan and an average body mass of 3.2 kg (7.1 lb) in a range of 2.4 to 6.35 kg (5.3 to 14.0 lb) but is similarly coloured. The largest male recorded was 14.5 kg (32 lb), a specimen obtained in Victoria. Reports of large birds, presumably males, were given by Tom Carter in the west (16 lb), a recorded range of 16–18 lb by E. F. Boehm in South Australia was exceeded in some specimens (28 lb). The smaller specimens in records are of an unwell adult weighing 9 lb, shot by Carter at Broomehill, and a healthy but small specimen of 7½ lb captured and weighed by Dominic Serventy and Hubert Whittell at Bridgetown in 1949. Although it is the largest extant flying land bird in Australia, this long-legged bird is the smallest species in the genus Ardeotis.
Voice[]
The voice of the courting male has been transliterated as "who-o-o-o".
Behavior[]
The species is mostly terrestrial and usually seen walking slowly alone or in pairs. When disturbed, Australian bustards often adopt a cryptic pose with neck erect and bill pointed skywards. They may stalk gradually away or run if alarmed, taking flight as a last resort. When leaving the ground they take to the air with heavy beats of the wings. A brooding female will crouch and move away if disturbed, flightless juveniles will remain still and rely on the camouflage of their plumage to evade detection. Despite the apparent labour in flying, they have strength and stamina that allows them to travel long distances. The roost is at a high point on an open plain or in trees when they are available. Greater numbers of the bird are seen during the breeding season. The habits of the bird are usually discreet and shy of disturbance, however, the display of males during the breeding season is a conspicuous performance that is accompanied by loud booming. The male is able to expand a sac at the neck to display their longer feathers as a swaying skirt, with the head held proud and upward facing, the wings are pointed toward the ground and tail feathers arched over the back; they stride about an area while adopting this posture and emit deep roaring noises. Males have been observed in close proximity during territorial disputes, using the breeding display and call to challenge each other, but the direct conflict seen in smaller bustard species is rare with this bird. One incident involving physical combat at a height around 25 metres was recorded in Arnhemland, after a period of posturing and chasing by the males in dispute, but this may be unusual behaviour due to the greater risk of injury in this larger species of bustard.
Ardeotis australis does not make any attempt to construct a nest. The clutch size is usually one egg, sometimes two, laid close to a small shrub or bush on unadorned ground. The shell is marked with olive-brown blotching and streaks over most of the surface, perhaps more completely covering the larger end of the egg, the background colour is a lighter shade of olive-brown or olive-green. Incubation of the brood is maintained by the female. The dimensions of the egg are 75 × 55 millimetres. The chick will leave the site after emerging from its shell to avoid predation, and relies on the mottled black and brown coloration of their downy plumage to evade detection by squatting and remaining motionless. Brooding females may be driven from the egg by the raptor Hamirostra melanosternon, the blackbreasted kite, who are able to throw or drop stones to break the shell and feed on the contents; the kite is also known to carry the broken shell to its nest. The species is strongly attracted to capers, fruit of the plant Capparis nummularia known as myandee or moonflower in the Australian northwest, and this behaviour is exploited by Indigenous peoples who dig pit traps around the bush and wait nearby to capture them. The omnivorous diet includes seeds and fruit of plants, a variety of insects, especially grasshoppers, lizards, young birds and small rodents.