Australasian Bittern Identification Guide
The Australasian Bittern is the icon bird of the southern Australian swamp, and its resonant booming call is said to have been the basis of the Aboriginal and colonialist myth of the Bunyip. It is a large, stocky, thick-necked heron with a cryptic plumage consisting of mottled buff, brown and dark brown streaks. The colour of the plumage varies slightly, particularly on the mantle and nape, from almost black to dark or rufous brown. Sexes are similar (though females are slightly smaller), while immatures are generally paler.
They are mostly seen singly or in pairs, usually within beds of reeds, rushes or sedges in freshwater wetlands, standing motionless among vegetation in the shallows. When flushed, birds rise awkwardly on large broad wings with rounded tips, their legs usually dangling, flying up to 10 metres above the vegetation. After a brief flight, they usually plunge out of sight into dense vegetation.
During spring and summer, males utter a distinctive, resonant bass booming call, preceded by up to three quick short, quieter gasp (not audible at distance). This call may occur in sets of several booms. Calling is considered to be associated with breeding and is most frequent at dawn and dusk, and may continue well into the night. Calls may carry over long distances in still air (has been likened to a distant foghorn). If heard well, it is unlikely to be confused with other species, though beware of the first part of the ‘thumping’ call of Purple Swamphen and of cows making untypical noises.
In Australia its range encompasses the Murray-Darling Basin and adjacent coastal regions from south-eastern Queensland to South Australia, Tasmania and south-western Western Australia
Similar species
The Australasian Bittern is most likely to be confused with a juvenile Nankeen Night Heron, which is much smaller, with a lighter build, and with its back spotted white. In flight its smaller body and narrower wings tend to create a much lighter appearance. It readily perches and roosts during the day in trees, whereas Australasian Bittern normally does not perch in trees.
The Black Bittern is smaller than both these species and has uniformly dark to black upperparts and a striking yellow streak on the sides of its head and neck. It usually inhabits heavily vegetated, often timbered, riparian or estuarine habitats.
Distribution of the Australasian Bittern from 1998-2011
Bird in flight. Note short neck and overall
stocky appearance. The birds fly strongly
usually up to 10m above vegetation. Feet Note posture and cryptic plumage (Mike extend beyond tail (Peter Fuller) Carter)
Birds have the ability to freeze in tall cover and Take off: birds explode from cover, become difficult to see. Panning across the face usually when observer is within 10 m of a reed bed within binoculars may reveal birds (Sonja Ross) (Rob Clemens)
Confusion species
Juvenile Nankeen Night Heron is smaller than Australian Bittern with a more Birds occasionally cross open ground. hunched stance. Back spotted with rather Note rufous plumage (Rob Clemens) than streaked (Nik Borrow)