The white-bellied heron (''Ardea insignis'') also known as the imperial heron or great white-bellied heron, is a large
heron
The herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera ''Botaurus'' and ''Ixobrychus ...
species living in the foothills of the
eastern Himalayas
]
The Eastern Himalayas extend from eastern Nepal across Northeast India, Bhutan, the Tibet Autonomous Region to Yunnan in China and northern Myanmar. The climate of this region is influenced by the monsoon of South Asia from June to September. ...
in
northeast India
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and
Bhutan
Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountainous ...
to northern
Myanmar
Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, Joh ...
. It inhabits undisturbed rivers and
wetlands
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...
. It has been listed as
Critically Endangered on the
IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
since 2007, because the global population is estimated at less than 300 mature individuals and threatened by habitat loss and human disturbance.
[ It is mostly dark grey with a white throat and underparts.
]
Taxonomy
The scientific name
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
''Ardea insignis'' was suggested by Brian Houghton Hodgson
Brian Houghton Hodgson (1 February 1800 or more likely 1801 – 23 May 1894) was a pioneer naturalist and ethnologist working in India and Nepal where he was a British Resident. He described numerous species of birds and mammals from the Himala ...
in 1844; he had presented a zoological specimen
A zoological specimen is an animal or part of an animal preserved for scientific use.
Various uses are: to verify the identity of a (species), to allow study, increase public knowledge of zoology.
Zoological specimens are extremely diverse. Exampl ...
to the British Museum
The British Museum is a public museum dedicated to human history, art and culture located in the Bloomsbury area of London. Its permanent collection of eight million works is among the largest and most comprehensive in existence. It docum ...
but a description was not published. This name was therefore considered a '' nomen nudum''. In 1878, Allan Octavian Hume
Allan Octavian Hume, CB ICS (4 June 1829 – 31 July 1912) was a British civil servant, political reformer, ornithologist and botanist who worked in British India. He was the founder of the Indian National Congress. A notable ornithologist, Hum ...
described the differences between the white-bellied and the great-billed heron
The great-billed heron (''Ardea sumatrana'') is a wading bird of the heron family, resident from southeast Asia to Papua New Guinea and Australia.
Description
left, Juvenile
The great-billed heron is a large bird, typically standing tall and ...
(''Ardea sumatrana''). The scientific name ''Ardea imperialis'' was suggested by E. C. Stuart Baker
Edward Charles Stuart Baker CIE OBE FZS FLS (1864 – 16 April 1944) was a British ornithologist and police officer. He catalogued the birds of India and produced the second edition of the ''Fauna of British India'' which included the introd ...
in 1929 to replace Hodgson's ''nomen nudum''. It was used until 1963, when Biswamoy Biswas commented on Sidney Dillon Ripley's synoptic list and noted that ''Ardea insignis'' Hume should be used, since its citation as a synonym of ''Ardea nobilis'' Blyth and ''Ardea sumatrana'' Raffles was based on a misidentification.
Description
The white-bellied heron has a uniform dark grey plumage, a whitish belly and long silvery or whitish plumes on the rear crown and lower foreneck. In breeding plumage, it has a greyish-white nape plume and elongated grey breast feathers with white centers. The face is greenish grey and the long bill black, but greenish near the base and tip; the iris is yellow to ochre, and the legs and feet are dull grey. Juveniles are browner above and have a paler bill and paler legs. In flight, it has a uniform dark grey upperwing and white underwing covert feather
A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which, as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts
The ear coverts are sm ...
s contrasting with dark grey flight feathers. The rump appears pale grey.
With a height of , it is the second largest heron.[ A white-bellied heron killed by the upper ]Ayeyarwady River
The Irrawaddy River ( Ayeyarwady River; , , from Indic ''revatī'', meaning "abounding in riches") is a river that flows from north to south through Myanmar (Burma). It is the country's largest river and most important commercial waterway. Orig ...
in 1903 had long wing bones, a wing spread of and a wingspan of . Its mean weight is estimated at .[
]
Distribution and habitat
The white-bellied heron inhabits the wetland
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...
s of tropical and subtropical forests in the foothills of the eastern Himalayas
]
The Eastern Himalayas extend from eastern Nepal across Northeast India, Bhutan, the Tibet Autonomous Region to Yunnan in China and northern Myanmar. The climate of this region is influenced by the monsoon of South Asia from June to September. ...
of northeast India
, native_name_lang = mni
, settlement_type =
, image_skyline =
, image_alt =
, image_caption =
, motto =
, image_map = Northeast india.png
, ...
and Myanmar
Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, Joh ...
. It also occurs in Bhutan
Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountainous ...
's low elevation Riparian zone, riparian environments below .
In Bhutan, it inhabits the basin of Sankosh River
Sankosh (also Mo Chu, and Svarnakosha) is a river that rises in northern Bhutan and empties into the Brahmaputra in the state of Assam in India. In Bhutan, it is known as the Puna Tsang Chu below the confluences of several tributaries near the ...
and its tributaries below . It was observed breeding in the Sankosh and Mangdechhu river basins; nests were found in chir pine (''Pinus roxburghii
''Pinus roxburghii'', commonly known as chir pine or longleaf Indian pine, is a species of pine tree native to the Himalayas. It was named after William Roxburgh.
Description
''Pinus roxburghii'' is a large tree reaching with a trunk diameter ...
''), champak ('' Magnolia champaca'') and bayur trees ('' Pterospermum acerifolium'') at elevations of .
In Assam, it was sighted several times in Kaziranga National Park
Kaziranga National Park is a national park in the Golaghat and Nagaon districts of the state of Assam, India. The park, which hosts two-thirds of the world's great one-horned rhinoceroses, is a World Heritage Site. According to the census held ...
during the winter seasons of 1994 and 1995. In Pobitora Wildlife Sanctuary, it was sighted regularly between 1996 and 2001. In Arunachal Pradesh, repeated sightings along Namdapha and Noa Dihing River
Dihing or Burhi Dihing (Dihong = wide river ) is a large tributary, about long, of the Brahmaputra River in Upper Assam in northeastern India. The river originates at above sea level in the Eastern Himalayas (the Patkai Hills) in Arunachal P ...
s indicate that Namdapha National Park
Namdapha National Park is a large protected area in Arunachal Pradesh of Northeast India. The park was established in 1983. With more than 1,000 floral and about 1,400 faunal species, it is a biodiversity hotspot in the Eastern Himalayas. The ...
is an important refuge and breeding site.
In northern Myanmar, it was observed along four streams in the Hkakabo Razi
Hkakabo Razi ( my, ခါကာဘိုရာဇီ, ; or ) is believed to be Myanmar's highest mountain. The -tall mountain is the highest mountain in Southeast Asia as well. It is located in the northern Myanmar state of Kachin in an outlyin ...
landscape between March 2016 and December 2020.
Behaviour and ecology
When disturbed, the white-bellied heron calls with a deep croak “ock ock ock ock urrrrrr”.
During the breeding season, the white-bellied heron calls during early morning hours, with the highest call density shortly before sunrise; it also frequently calls in late night hours, but rarely during the day.
During the day, it roosts for long periods of up to six hours on bare sandy patches, large rocks, logs and trees, and sometimes lays down on the sternum
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...
.[ In the night, it sleeps with the head pressed on the breast and one leg grasping on the perch, while the other is tucked up in the belly. Adult white-bellied herons roost alone, and juveniles roost in pairs.]
It prefers foraging in shallow river sections with multiple about wide channels, in shallow ponds and pools within river islands and on island edges.[ It feeds mostly on '']Schizothorax
''Schizothorax'' is a genus of cyprinid fish found in southern and western China, through northern South Asia (Himalaya) and Central Asia, to Iran, with a single species, ''S. prophylax'', in Turkey.Yang, J.; J.X. Yang; and X.Y. Chen (2012). A re ...
'' carps all year through, but also on brown trout
The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morph ...
(''Salmo trutta'') in spring and ''Garra
''Garra'' is a genus of fish in the family Cyprinidae. These fish are one example of the "log suckers", sucker-mouthed barbs and other cyprinids commonly kept in aquaria to keep down algae. The doctor fish of Anatolia and the Middle East belo ...
'' fish species during the summer. Feeding bouts last for 5 to 58 minutes.
Threats
The white-bellied heron is threatened by habitat loss
Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
, increasing disturbance and habitat degradation
Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
due to conversion of wetlands for agriculture and expansion of settlements, harvesting of wetland resources and poaching
Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights.
Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...
. It is locally extinct
Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...
in Nepal and possibly also in Bangladesh.[
In Bhutan, four large ]hydropower
Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water to Electricity generation, produce electricity or to power machines. This is achieved by energy transformation, converting the Pot ...
projects are located in important white-bellied heron habitat, and rivers are exploited for gravel and sand mining
Sand mining is the extraction of sand, mainly through an open pit (or sand pit) but sometimes mined from beaches and inland dunes or dredged from ocean and river beds. Sand is often used in manufacturing, for example as an abrasive or in conc ...
.[ Nesting sites have been negatively affected by forest fires.][
]
Conservation
In India, the white-bellied heron is protected under Schedule 1 of the Wild Life (Protection) Act, 1972
The Wild Life (Protection) Act, 1972 is an Act of the Parliament of India enacted for protection of plants and animal species. Before 1972, India had only five designated national parks. Among other reforms, the Act established scheduled pr ...
.[ In Myanmar, it is afforded the highest level of legal protection since 1994.][ It has been listed as Critically Endangered on the ]IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
since 2007 as the global population is thought to consist of less than 250 mature individuals and to decline rapidly.[
A white-bellied heron was hatched in captivity for the first time in May 2011 and released in September 2011 in Bhutan's ]Punakha District
Punakha District ( Dzongkha: སྤུ་ན་ཁ་རྫོང་ཁག་; Wylie: ''Spu-na-kha rdzong-khag'') is one of the 20 dzongkhags (districts) comprising Bhutan. It is bordered by Thimphu, Gasa, and Wangdue Phodrang Districts. The do ...
.[
]
References
External links
*
{{Taxonbar, from=Q852874
white-bellied heron
The white-bellied heron (''Ardea insignis'') also known as the imperial heron or great white-bellied heron, is a large heron species living in the foothills of the eastern Himalayas in northeast India and Bhutan to northern Myanmar. It inhabits u ...
Birds of Bhutan
Birds of Northeast India
white-bellied heron
The white-bellied heron (''Ardea insignis'') also known as the imperial heron or great white-bellied heron, is a large heron species living in the foothills of the eastern Himalayas in northeast India and Bhutan to northern Myanmar. It inhabits u ...