This largest stork in Sri Lanka is very rare on the island. The estimated number of birds of this species in Sri Lanka is only about 50. Almost all of them live in the national parks Kumana, Yala and Bundala in the very South-East of the island, there are only a few records of sightings at Annaiwilundawa bird sanctuary between Chilaw and Puttalam in the North-Western Province. Though very small, the population in this most important wildlife area of Sri Lanka has remained stable for several decades. The species is nearly extinct in Bangladesh and mainland Southeast Asia. But it is evaluated only as “near threatened” on the international IUCN Red List, this means just below “least concern” and above “vulnerable”. The Black-necked Stork is not an endangered species due to larger populations of its two races in India and Australia. The Southasian race of the Black-necked Stork, Ephippiorhynchus asiaticus asiaticus, is still widespread - though declining - along the Chambal River in south-eastern Rajasthan and south-western Uttar Pradesh and northen Madhya Pradesh in India, which is a densely cultivated area.
Strangely enough, no nests have been found in Sri Lanka until now, though this stork’s nests are huge and it prefers Banyan and Bo trees, which are not at all rare in Sri Lanka. However, individuals have been seen throughout the year, in both monsoon seasons, and few immatures have been spotted. too. Thus it is likely that this species is resident and breeding in Sri Lanka. It is estimated that there are 4–8 breeding pairs in Yala National Park. Breeding season in India is varying according the monsoon and water conditions, but mainly starting in September. In India, the Black-necked Stork builds a solitary nest in a large tree 6-25 m above ground, not neccesarily near water.
Known from observations in mainland India, the Black-necked Stork is one of the few storks that is strongly territorial. It is only known from Bangla Desh that this species, when becoming rare, can become vagrant, too.
The size of the Sri Lankan Black-necked Stork is between 130 and 135 cm, whereas Indian individuals can even reach 150 cm. The wingspan is 230 cm, average weight is about 4 kilogram.
The adult female differs from the adult male only in having a yellow rather than brown iris, and is slightly smaller in size. Juveniles younger than six months have a brownish iris. The difference in iris colour among the sexes is a charakteristic of the African Ephippiorhynchi, too, but not of other stork species. Charles Darwin used it as one of the examples of sexual dimorphism among birds.
The preferred habitats are freshwater marshes and shallow lakes and tanks, in Sri Lanka sometimes lagoons and in India wide shallow rivers, too. In cultivated areas, flooded rice paddies are used for foreaging during the monsoon season additionally. Black-necked Storks wade slowly and sedately while probing in shallow water and among aquatic vegetation with its bill open at the tip. Fish, frogs, crabs, coots and other small animals form the food of the Black-necked Stork. This non-social stork forages singly, but pairs remain within sight of each other. In India, family parties of up to 15 individuals can sometimes be seen after breeding season or due to sinking water levels.
Black-necked Storks share the typical behaviour of other storks, clappering of the mandibles during the mating season and being silent otherwise. Black-necked Storks usually rest on their hocks. When disturbed, Black-necked Storks stretch out their necks. These animals are usually very wary. So you need good luck, like Kapila, to see them in Sri Lanka.