Migratory, partially migratory, and dispersive; erratic at times. Population resident in coastal lowlands of west Mediterranean; minority, numbers varying with weather, winter Camargue, most Andalucía and north-west Africa. Partial emigration from Camargue begins July, continues to October or later in cold weather; return movement apparent March, but non-breeders abroad all months. Those wintering in east Mediterranean basin, chiefly Turkey, Cyprus, Cyrenaica (Libya) and northern Egypt, presumably of Asiatic origins.
Non-breeders present all year in wintering areas, while throughout range prone to irregular movements in response to temperature and water-level changes. Most occurrences in central and north Europe probably escapes, especially since majority adults, whereas immatures wander most. Occasional erratic influxes occur, e.g. May 1924, when noted Rhône valley, France, and flock of c. 60 immatures Switzerland; autumn 1935, when small flocks of juveniles reached Germany.
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