Australasian bittern

Botaurus poiciloptilus

Photo by Marlene Lyell (Flickr)

Common name:
Australasian bittern (en); abetouro-australiano (pt); butor d'Australie (fr); avetoro australiano (es); Australische rohrdommel (de)

Taxonomy:
Order Ciconiiformes
Family Ardeidae

Range:
This species is found throughout most of New Zealand, in New Caledonia and in Australia, in south-western Western Australia and from southern Queensland to Tasmania and south-eastern South Australia.

Size:
These birds are 66-76 cm long and have a wingspan of 105-120 cm. The females weigh 570-1.130 g, while the males weigh 880-2.080 g.

Habitat:
The Australasian bittern is found in shallow, freshwater wetlands with lots of tall reeds, rushes and other dense vegetation, occasionally also using estuaries and other tidal wetlands and rice paddies. They are present from sea level up to an altitude of 800 m.

Diet:
They forage mainly at night, hunting frogs, fishes, crayfish, snails and aquatic insects. It has also been recorded feeding on lizards, birds, rats, mice, leaves and fruit.

Breeding:
Australasian bitterns breed in September-February. They are monogamous, solitary nesters, nesting in a well-constructed saucer of flat pieces of reeds or rushes that are laid across one another and may be sheltered above by stems of the surrounding vegetation. It is placed 30 cm above the water. The female lays 3-6 olive-brown eggs, which she incubates alone for about 25 days. The chicks are fed by the female alone and fledge 7 weeks after hatching.

Conservation:
IUCN status - EN (Endangered)
This species has a large breeding range and a global population estimated at 1.000-2.500 individuals. The population trends are unknown for the small New Caledonian population, whilst in New Zealand the species is suspected to be stable. In Australia, the population has declined by over 70% since the 1970s, mainly due to wetland drainage for agriculture, as well as changes brought about by high levels of grazing and salinisation of swamps. Human disturbance and predation by introduced red foxes may also pose a problem to this species.