The Black Bittern is a heron, dark grey to black in colour, with buff streaks on the throat and a characteristic yellow streak on the sides of the head and down the neck. The feathers on the crown and lower neck are almost plumes. The legs are dark. The female is paler than the male, with a more yellow wash on the underparts. The species has a characteristic booming call that is mainly heard during the breeding season, at day or night. The colour alone readily distinguishes it from the other two much paler bittern species. They are found from the Indian subcontinent to southern China, Southeast Asia and northern Australia with some northern population wintering in Southeast Asia.
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They are often secretive, hiding in reeds for long periods of time.
Inhabits both terrestrial and estuarine wetlands, generally in areas of permanent water and dense vegetation. Where permanent water is present, the species may occur in flooded grassland, forest, woodland, rainforest and mangroves.
During the day, roosts in trees or on the ground amongst dense reeds. When disturbed, freezes in a characteristic bittern posture (stretched tall, bill pointing up, so that shape and streaked pattern blend with upright stems of reeds), or will fly up to a branch or flush for cover where it will freeze again.
Generally solitary, but occurs in pairs during the breeding season, from December to March.
Like other bitterns, but unlike most herons, nesting is solitary. Nests, built in spring are located on a branch overhanging water and consist of a bed of sticks and reeds on a base of larger sticks. Between three and five eggs are laid and both parents incubate and rear the young.
Black Bitterns feed on a wide range of small animals, but mainly fish and amphibians. Feeds on frogs, reptiles, fish and invertebrates, including snails, dragonflies, shrimps and crayfish, with most feeding done at dusk and at night.
They stalk prey slowly or stand and wait for prey to emerge, but may sometimes plunge at it from a perch, before stabbing it with their sharp bills.
Nesting timing differs geographically. In the north, breeding is triggered by the advent of the monsoon, at any time between May and September. In Sri Lanka nests have been found in April, May in Java, February in New Guinea, and September to January In Australia. Overall it breeds in densely vegetated, secluded wetlands. But its nesting habitat is surprisingly diverse, depending mostly on having dense cover near water. In India and Sri Lanka, it nests in reeds, thorn bush or cane breaks low over water. In China, it nests in bamboo and trees as high as 6m. In Australia nests are located in gums standing in water and in mangroves. It occasionally nests away from water and is it not unusual to nest close to human habitation.
Black Bitterns nest solitarily or in loose nesting groups. At places the nest interspersed in mixed colonies with other herons. The nest is a platform, 23- 35 cm wide and 7.5 cm, with a shallow central depression. It is made of twigs or reeds. The nest is built by both birds. Its placement is variable, from 1 to 15 m above the water or ground.
It adopts the Bittern posture when disturbed and when alarmed, raises and lowers its crest. It is likely that the plumes at the base of the neck are used during courtship display, but there is no information.
The eggs are white, although there have been reports of a blue tinge to some. As recorded, they vary in size averaging 41.6 X 31.4 mm in India and Myanmar, 45 X 35 mm in Australia, and 43 X 34 mm in New Guinea. Clutch size is 3 - 6 eggs. Although it is probably usually single brooded, double broods occur. Incubation is by both sexes. Both sexes feed the chicks regurgitated food. The incubating bird sits very tightly and the chicks. The chicks soon leave the nest if disturbed.
The black bittern (Ixobrychus flavicollis), locally known as Kalhu Raabondhi is a protected bird in Maldives since 22nd May 2003.
This species is evaluated as ‘Least Concern’ by IUCN.