Indian Pond Heron
In non-breeding plumage (Sri Lanka)
Breeding plumage in (Kolkata, India)
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Ciconiiformes
Family:	Ardeidae
Genus:	Ardeola
Species:	A. grayii
Binomial name
Ardeola grayii (Sykes, 1832)
Synonyms
Ardeola leucoptera

The Indian Pond Heron or Paddybird (Ardeola grayii) is a small heron. It is of Old World origins, breeding in southern Iran and east to India, Burma, Bangladesh and Sri Lanka. They are widespread and common but can be easily missed when the stalk prey at the edge of small water-bodies or even when the roost close to human habitations. They are however distinctive when put to flight, the bright white wings flashing in contrast to the cryptic streaked olive and brown colours of the body. The camouflage is so excellent that they will often allow humans to approach very close before taking to flight, and this has resulted in folk names and beliefs that the birds are short-sighted or blind.^[2][3]

In Sri Lanka the bird is called Kana Koka (translates to 'Half-blind Heron') by the Sinhala speaking community ^[4]

[edit] Description

In Breeding plumage with red legs in Kolkata, West Bengal, India.

They appear stocky with a short neck, short thick bill and buff-brown back. In summer, adults have long neck feathers. Its appearance is transformed from their dull colours when they take to flight, when the white of the wings makes them very prominent. It is very similar to the Squacco Heron, Ardeola ralloides, but is darker-backed. To the east of its range, it is replaced by the Chinese Pond Heron, Ardeola bacchus.

When flushed the contrasting white wings flash into view

During the breeding season, there are records of individuals with red legs. The numbers do not suggest that this is a normal change for adults during the breeding season and some have suggested the possibility of it being genetic variants.^[5][6][7][8]

Usually hunched, they appear short necked

Erythristic plumage has been noted.^[9] The race phillipsi has been suggested for the populations found in the Maldives, however this is not always recognized.^[10] It forms a superspecies with the closely related Chinese Pond Heron, Javan Pond Heron and the Madagascar Pond Heron.

They are very silent but may give a harsh croak when flushed or near their nests.^[10]

This bird was first described by Colonel W. H. Sykes in 1832 and given its scientific name in honour of John Edward Gray. Karyology studies indicate that Pond Herons have 68 chromosomes (2N).^[11]

[edit] Behaviour and ecology

Pair at Nest in Kolkata, West Bengal, India.

They are very common in India, and are usually solitary foragers but numbers of them may sometimes feed in close proximity during the dry seasons^[12] when small wetlands have a high concentration of prey. They are semi-colonial breeders. They may also forage at garbage heaps. During dry seasons, they sometimes take to foraging on well watered lawns or even dry grassland. When foraging, they allow close approach and flush only at close range. They sometimes form communal roosts, often in avenue trees over busy urban areas.^[13]

[edit] Food and feeding

Large numbers in a drying pond

The Indian Pond Heron's feeding habitat is marshy wetlands. They usually feed at the edge of ponds but make extensive use of floating vegetation such as Water hyacinth to access deeper water. They may also on occasion swim on water or fish from the air and land in deeper waters.^{[14][15][16][17]} They have also been observed capturing leaping fishes by capturing them in flight.^{[18] [19]} Sometimes, they may fly low over water to flush frogs and fishes towards the shore before settling along the shoreline.^[20]

The primary food of these birds includes crustaceans, aquatic insects, fishes, tadpoles and sometimes leeches (Herpobdelloides sp.).^[21] Outside wetlands, these herons feed on insects (including crickets, dragonflies^[22] and bees^[23]), fish (Barilius noted as important in a study in Chandigarh) and amphibians.^[24]

[edit] Breeding

The breeding season is prior to the Monsoons. They nest in small colonies, often with other wading birds, usually on platforms of sticks in trees or shrubs. Most nests are built at a height of about 9 to 10 m and in large leafy trees. The nest material is collected by the male while the female builds the nest. 3-5 eggs are laid.^[25] The eggs hatch asynchronously, taking 18 to 24 days to hatch. Both parents feed the young.^[26] Fish are the main diet fed to young.^[12]

[edit] Movements

Nocturnal movements of Pond Herons have been noted along the coast near Chennai.^[27]

[edit] Mortality factors

They have few predators and injured birds may be taken by birds of prey.^[28]

An arbovirus "Balagodu", trematodes^[29] and several other parasites have been isolated from the species.^{[30][31][32][33][34]} Antibodies to Japanese Encephalitis/West Nile Virus has been detected in Pond Herons and Cattle Egrets from southern India.^[35] Heavy metal pollution appears to be indicated particularly in the tail feathers.^[36]

[edit] References

[edit] Other sources

Wikimedia Commons has media related to: Ardeola grayii

• Lamba, B.S. (1963) Nidification of some Indian birds. No.6. The Indian Pond Heron or Paddy bird Ardeola grayii (Sykes). Pavo 1(1): 35-43.
• de Boer LEM, van Brink JM (1982) Cytotaxonomy of the Ciconiiformes (Aves), with karyotypes of eight species new to cytology. Cytogenet Cell Genet 34:19-34 (DOI: 10.1159/000131791)
• Parasharya,BM; Bhat,HR (1987) Unusual feeding strategies of the Little Egret and Pond Heron. Pavo 25(1&2), 13-16.

[edit] External links

• Internet Bird Collection