Black-backed Bittern
Botaurus dubius
Tiny secretive heron. Adult male has black back, brown neck, and streaked reddish-brown underparts. In flight, pale upperwing coverts contrast with dark back and dark flight feathers. Female and juvenile lack black back and have streaked underparts. Most commonly observed in early morning or evening clambering along the edge of reed beds. Calls include a distinctive repeated growling or croaking bark.
Identification
The species measures from 25 to 36 cm (9.8 to 14.2 in), has a total weight of 60–120 g (2.1–4.2 oz), averaging 84 g (3.0 oz). This is a very small bittern and one of the smallest herons in the world. The adult male has largely black upperparts, including a black cap, while the underparts, as well as the neck, breast and the sides of the head, are rich chestnut. There are large buff patches on the shoulders, conspicuous in flight. The female is duller, brown and streaked on back and crown; immature birds are similar. The irides are yellow, the bill is yellow with a black culmen, and the feet and legs greenish-yellow.
Taxonomy
The bittern has sometimes been regarded as a subspecies of the little bittern (Ixobrychus minutus), or of the New Zealand little bittern (I. novaezelandiae). However, molecular evidence has shown it to be more closely related to the yellow bittern (I. sinensis) than to the African and Palaearctic forms of the little bittern, and it is now recognised as a full species.
- Scientific name
- Botaurus dubius
- Authority
- Mathews, 1912
- Order
- Pelecaniformes
- Family
- Ardeidae
- Genus
- Botaurus
Range and habitat
The birds are mainly found in freshwater wetlands, where they inhabit dense emergent vegetation of reeds and sedges, and inundated shrub thickets. They are also occasionally found in brackish and saline wetlands such as mangrove swamps, Juncus-dominated salt marsh and the wooded margins of coastal lagoons. In Australia the bittern is found in the south-east of the continent, with most records deriving from the Murray-Darling Basin, as well as patchily along the east coast, and in south-west Western Australia where it is locally common on the Swan Coastal Plain. Some scattered records are given from elsewhere, including coastal locations in the Kimberley region, the Top End, and the Torres Strait islands, with vagrants occasionally reaching Lord Howe Island and New Zealand.<p>Apart from records of vagrants, circumstantial evidence that at least part of the population makes long-distance seasonal migrations is that most sightings, and the highest reporting rates, of the bitterns in southern Australia occur in spring and summer, with the birds largely absent in autumn and winter. There are few breeding records from the Australian tropics.<p>In New Guinea the bittern is found seasonally in the reed beds of the Waigani Swamp near Port Moresby from November to April, only being reliably recorded elsewhere on the island from the lowlands of the Trans-Fly region. No firm breeding records are from New Guinea, though a specimen taken in the middle Fly River lagoons was of a bird ready to lay, indicating breeding in the Fly River marshes in September. The lack of good breeding records suggests that at least some birds in New Guinea are seasonal migrants from Australia.<p>The bittern was sighted in New Caledonia in 2001, where it bred.
- Migration
- Complete migrants
Behavior
Migration pattern: Complete migrants.
Conservation
Population trend: declining.
- Population trend
- declining
Photos
Distribution
Bird Calls
Other Birds
Rufous-bellied Helmetshrike
Prionops rufiventris
A boldly patterned helmetshrike of lowland forests, often seen in small vocal groups. The bill is red and the head and chin are overall silvery gray. Has a black neck band and black wings, back, and tail. The chest is white and the belly, vent, and legs are reddish. Similar to the Red-billed Helmetshrike, with which it co-occurs locally in Cameroon, but Rufous-bellied Helmetshrike can be identified by its silvery gray chin and head (including below the eye) and the more extensive reddish coloration on its belly. Calls consist of liquid whistles and repeated grating “chew-two” calls.
Pitcairn Reed Warbler
Acrocephalus vaughani
A large cold-toned warbler with grayish-brown upperparts, yellowish-buff underparts, and variably white wings and tail. Irregular whitening of wings and tail give it a messy appearance. Found primarily in patches of tall forest, avoiding open areas. Voice is a harsh, scolding “chak, chak.” Does not sing.
Moustached Antpitta
Grallaria alleni
Medium-sized antpitta. Typical antpitta shape: plump and short-tailed with long legs, like a grapefruit on stilts. Mostly brown with a brighter cinnamon belly and grayish crown. Note blotchy white mustache stripe. Very similar in appearance to Scaled Antpitta but typically occurs at slightly higher elevations. Moustached has a less pronounced scaly pattern on the upperparts, browner cheeks, and a slower, higher-pitched song without a stutter in the middle than Scaled Antpitta. Fairly rare and local within limited range in the Andes of Colombia and Ecuador. Occurs in mossy cloud forest in the lower subtropics from around 1,850–2,000 m. Very rarely seen; typically stays hidden in the dense understory, occasionally hopping onto forest trails at dawn or dusk.
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