Australasian Bittern (Botaurus poiciloptilus)

Australasian Bittern

[order] CICONIIFORMES | [family] Ardeidae | [latin] Botaurus poiciloptilus | [authority] Wagler, 1827 | [UK] Australasian Bittern | [FR] Butor d’Australie | [DE] Australische Rohrdommel | [ES] Avetoro Australiano | [NL] Australische Roerdomp

Subspecies

Genus Species subspecies Region Range
Botaurus poiciloptilus AU sw, se Australia, New Zealand

Genus

Botaurus is a genus of bitterns, a group of wading bird in the heron family Ardeidae. It has a single representative species in each of North America, Central and South America, Eurasia and Australasia. The two northern species are partially migratory, with many birds moving south to warmer areas in winter. The four Botaurus bitterns are all large chunky, heavily streaked brown birds which breed in large reedbeds. They are secretive and well-camouflaged, and despite their size they can be difficult to observe except for occasional flight views.

Physical charateristics

The Australasian Bittern is a large, stocky bird, reaching up to 75 cm in length. It has a long, thick neck and a straight, brownish-yellow bill. Its upper surface is mottled brown and its undersurface is buff, with dark brown stripes, except for a pale throat. The eyes are yellow and there is a pale eyebrow. The feet and legs are pale green.

Listen to the sound of Australasian Bittern

[audio:http://www.planetofbirds.com/MASTER/CICONIIFORMES/Ardeidae/sounds/Australasian Bittern.mp3]

Copyright remark: Most sounds derived from xeno-canto


wingspan min.: 105 cm wingspan max.: 118 cm
size min.: 66 cm size max.: 76 cm
incubation min.: 23 days incubation max.: 27 days
fledging min.: 60 days fledging max.: 66 days
broods: 1   eggs min.: 3  
      eggs max.: 6  

Range

Australasia : Southwest, Southeast Australia, New Zealand. Botaurus poiciloptilus occurs in the wetlands of southern Australia, New Zealand and New Caledonia (to France)

Habitat

It has fairly specific habitat preferences, preferring shallow, vegetated freshwater or brackish swamps where there is a mixture of short and tall emergent sedges and rushes. It has been recorded in paddies in the Murray Darling basin, but it is not thought to use such habitats for breeding

Reproduction

The nest is constructed of trampled reeds and rushes and is generally located amongst dense vegetation over shallow water. The clutch size is thought to be between 4 and 5 eggs. The egs are incubated for about 25 days, the young fledge about 7 weeks after hatching, Males mate usually with one female, but up to 7 different partners has bee nrecorded.

Feeding habits

It feeds, mostly at night, on fish, eels, frogs, freshwater crayfish and aquatic insects. The population seems to increase rapidly in good years and decline rapidly in poor ones

Video Australasian Bittern

httpv://www.youtube.com/watch?v=QKGFXibbiE4

copyright: PGLaouto


Conservation

This species is listed as Endangered because it has a very small and rapidly declining population owing to loss and degradation of its wetland habitats. Urgent action is a priority to halt declines in Australia.
In New Zealand, the estimated population was between 580-725 individuals in 1980. The population on New Caledonia is not thought to exceed 50 individuals. Following apparently rapid declines, the Australian population is now thought to number fewer than 1,000 mature individuals. In Australia and New Zealand, the main threats are wetland drainage for agriculture, as well as changes brought about by high levels of grazing and salinisation of swamps. In Australia, the species appears able to adapt to the availability of ephemeral wetlands, but is likely to be particularly sensitive to the destruction of drought refugia. Loss of these habitats may explain its decline in Western and South Australia. The Murray-Darling basin, a former stronghold of the species, has suffered consecutive droughts in recent years and over-extraction of water is an ongoing problem. Shooting and flying into powerlines are additional contributory causes2, but hunting pressure is very low.
Australasian Bittern status Endangered

Migration

Sedentary with some post-breeding dispersal. In some very wet years irruptive movements have been recorded, but not seasonally.

Distribution map

Australasian Bittern distribution range map

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