The grey-headed gull (Chroicocephalus cirrocephalus), also known as the grey-hooded gull, is a small gull which breeds patchily in South America and Africa south of the Sahara. It is not truly migratory, but is more widespread in winter. This species has occurred as a rare vagrant to North America, Italy and Spain. As is the case with many gulls, it has traditionally been placed in the genus Larus.
This locally abundant gull breeds in large colonies in reedbeds and marshes, and lays two or three eggs in a nest, which can be on the ground or floating. Like most gulls, it is highly gregarious in winter, both when feeding and in evening roosts. Although it is predominantly coastal or estuarine, it is not a pelagic species, and is rarely seen at sea far from land.
Flocks numbering hundreds or thousands of these gulls can form when the feeding conditions are appropriate. This gull takes two years to reach maturity. First year birds have a black terminal tail band, and more dark areas in the wings. In flight, the wings are broader and held flatter than those of black-headed gull. This is a noisy species, especially at colonies.
Source : wikipedia