Asian Openbill stork

Description:

The Asian openbill or Asian openbill stork (Anastomus oscitans) is a large wading bird in the stork family Ciconiidae. This distinctive stork is found mainly in the Indian subcontinent and Southeast Asia. It is greyish or white with glossy black wings and tail and the adults have a gap between the arched upper mandible and recurved lower mandible. Young birds are born without this gap which is thought to be an adaptation that aids in the handling of snails, their main prey. Although resident within their range, they make long distance movements in response to weather and food availability. 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.[8] The tail consists of twelve feathers and the preen gland has a tuft.[9] 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)

Habitat:

Yala National Park. coastal lowlands. The Yala area is mostly composed of metamorphic rock belonging to the Precambrian era and classified into two series, Vijayan series and Highland series. Reddish brown soil and low humic grey soil are prominent among six soil types. Yala is situated in the lowest peneplain of Sri Lanka, which extends from Trincomalee to Hambantota. Topographically the area is a flat and mildly undulating plain that runs to the coast with elevation is 30 metres (98 ft) close to the coast while rising in the interior to 100–125 metres (328–410 ft). The national park is situated in the dry semi-arid climatic region and rain is received mainly during the northeast monsoon. The mean annual rainfall ranges between 500–775 millimetres (19.7–30.5 in) while the mean temperature ranges between 26.4 °C (79.5 °F) in January to 30 °C (86 °F) in April. It is windier in Yala, during the southwest monsoon compared to the wind during the northeast monsoon with wind speeds from 23 kilometres per hour (14 mph) to 15 kilometres per hour (9.3 mph). Water is abundant after the northeast monsoon, but during the dry season surface water becomes an important factor. The bodies of surface water appear in the forms of streams, tanks, waterholes, rock pools, and lagoons. Waterholes occur in low lying places while rock pools of varying size are capable of containing water year-round, and are hence an important source of water for elephants. For many water birds and water buffaloes natural waterholes are ideal habitats. Such reservoirs are largely concentrated to the Block I followed by Block II. Several tanks are there including, Maha Seelawa, Buthawa, Uraniya, and Pilinnawa tanks. Many rivers and streams flow in a southeasterly direction, originating in the highlands of adjacent Uva and central hills. Kumbukkan Oya in the east and Menik River and its tributaries in the west flow across the park, and provide an important water source in the dry season to wild animals of the park. Normally the streams of the park are dry during the drought season. These rivers and streams exhibit a degree of runoff fluctuations between wet and dry seasons. Kumbukkan Oya discharges seven times as much water in the rainy season than in the dry season. A number of lagoons are situated along the coast line of the park.