The woolly-necked stork or whitenecked stork (Ciconia episcopus) is a large wading bird in the stork family Ciconiidae. It breeds singly, or in small loose colonies. It is distributed in a wide variety of habitats including marshes in forests, agricultural areas, and freshwater wetlands.
The woolly-necked stork is a broad winged soaring bird, which relies on moving between thermals of hot air for sustained long distance flight. Like all storks, it flies with its neck outstretched. It has also been observed to 'roll, tumble and dive at steep angles' in the air with the wind through its quills making a loud noise. Adult birds have also been observed diving from nests before flying away abruptly in a 'bat-like flight'.
This species is largely seen as single birds, in pairs, or in small family groups of 4-5, and flocks are uncommon. In agricultural landscapes, the species occurs mostly as very small flocks (< 5 birds), though flocks of over 10 birds occur commonly. Flocking is affected by different factors in different areas. In more arid areas, most of the flocks occur in the summer when few wetlands are remaining, whereas in areas with more water, flocks occur largely in winter after chicks have fledged from nests. They often associate with wintering stork species including the Black and White Storks.
Source : Wikipedia