Asian Openbill
Anastomus oscitans
A relatively small stork species with a grayish to white body and black wings and tail with a hint of gloss. The Asian Openbill gets its name from a distinctive gap in the dull grayish yellow bill. Note the pinkish legs. Asian Openbills inhabit wetland habitats including shallow marshes, flooded agricultural fields, and lakes. From a distance they could be confused with herons, but they can be clearly distinguished from herons by their feeding habits—wading slowly through shallow water. Soars frequently, often in large dense flocks; note extended neck, unlike retracted neck of herons and egrets.
Identification
The Asian openbill stork is predominantly greyish (non-breeding season) or white (breeding season) with glossy black wings and tail that have a green or purple sheen. The name is derived from the distinctive gap formed between the recurved lower and arched upper mandible of the beak in adult birds. Young birds do not have this gap. The cutting edges of the mandible have a fine brush like structure that is thought to give them better grip on the shells of snails. The tail consists of twelve feathers and the preen gland has a tuft. The mantle is black and the bill is horn-grey. At a distance, they can appear somewhat like a white stork or Oriental stork. The short legs are pinkish to grey, reddish prior to breeding. Non-breeding birds have a smoky grey wings and back instead of white. Young birds are brownish-grey and have a brownish mantle. Like other storks, the Asian openbill is a broad-winged soaring bird, which relies on moving between thermals of hot air for sustained flight. They are usually found in flocks but single birds are not uncommon. Like all storks, it flies with its neck outstretched. It is relatively small for a stork and stands at 68 cm height (81 cm long).
Taxonomy
The Asian openbill was described by the French polymath Georges-Louis Leclerc, Comte de Buffon in 1780 in his Histoire Naturelle des Oiseaux from a specimen collected in Pondichery, India. The bird was also illustrated in a hand-coloured plate engraved by François-Nicolas Martinet in the Planches Enluminées D'Histoire Naturelle which was produced under the supervision of Edme-Louis Daubenton to accompany Buffon's text. Neither the plate caption nor Buffon's description included a scientific name but in 1783 the Dutch naturalist Pieter Boddaert coined the binomial name Ardea oscitans in his catalogue of the Planches Enluminées. The Asian openbill is now placed in the genus Anastomus that was erected by the French naturalist Pierre Bonnaterre in 1791. The genus name Anastomus is from the Ancient Greek αναστομοω anastomoō meaning "to furnish with a mouth" or "with mouth wide-opened". The specific epithet oscitans is the Latin word for "yawning".
- Scientific name
- Anastomus oscitans
- Authority
- (Boddaert, 1783)
- Order
- Ciconiiformes
- Family
- Ciconiidae
- Genus
- Anastomus
Range and habitat
The usual foraging habitats are inland wetlands and are only rarely seen along river banks and tidal flats. On agricultural landscapes, birds forage in crop fields, irrigation canals, and in seasonal marshes. Birds may move widely in response to habitat conditions. Young birds also disperse widely after fledging. Individuals ringed at Bharatpur in India have been recovered 800 km east and a bird ringed in Thailand has been recovered 1500 km west in Bangladesh. Storks are regularly disoriented by lighthouses along the southeast coast of India on overcast nights between August and September. The species is very rare in the Sind and Punjab regions of Pakistan, but widespread and common in India, Sri Lanka, Nepal, Bangladesh, Myanmar, Thailand and Cambodia. It has recently expanded its range into southwestern China. In Thirunavaya Lotus Lake Wetland Malappuram district of Kerala state in India, they are mostly seen in the months of September–February season<p>Asian Openbills appear to be susceptible to dying during hailstorms. In Xishuangbanna, in south China, 45 Asian Openbills were counted dead after a hailstorm, but carcasses of other bird species were not seen.
- Migration
- Resident species
Conservation
- Population trend
- unknown
Photos
Distribution
Bird Calls
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