Behaviour Northern populations of this species make long-distance migratory movements, travelling southwards to their wintering grounds between August and November and returning to their breeding areas between March and April (Hayman et al. 1986). In more temperate regions the species is sedentary or only locally dispersive however (del Hoyo et al. 1996). The species breeds solitarily or in loose colonies of 2-50 or occasionally up to several hundred pairs (Urban et al. 1986, del Hoyo et al. 1996). It is typically a gregarious species, occurring in small groups (Snow and Perrins 1998) (up to 15 individuals) (Urban et al. 1986, del Hoyo et al. 1996) or larger flocks of several hundred up to a thousand individuals on migration, during the winter (Urban et al. 1986, Snow and Perrins 1998) and at nightly roosts (Urban et al. 1986). Habitat Breeding The species typically breeds in shallow freshwater and brackish wetlands with sand, mud or clay substrates and open margins, islets or spits near water level (Snow and Perrins 1998). Suitable habitats include marshes and swamps, shallow lake edges, riverbeds, flooded fields (del Hoyo et al. 1996), irrigated areas (Snow and Perrins 1998), sewage ponds (del Hoyo et al. 1996) and fish-ponds (Snow and Perrins 1998). The species may also breed around alkaline and high-altitude (montane) lakes (del Hoyo et al. 1996) or in more saline environments such as river deltas, estuaries (Snow and Perrins 1998), coastal lagoons (Johnsgard 1981, Snow and Perrins 1998) and shallow coastal pools with extensive areas of mudflats, salt meadows (Johnsgard 1981), saltpans, coastal marshes (del Hoyo et al. 1996) and swamps (Snow and Perrins 1998). Non-breeding Outside of the breeding season the species occupies the shores of large inland waterbodies and estuarine or coastal habitats (del Hoyo et al. 1996) such as river deltas (Snow and Perrins 1998), coastal lagoons (Johnsgard 1981, Snow and Perrins 1998) and shallow freshwater or brackish pools with extensive areas of mudflats, salt meadows (Johnsgard 1981), saltpans, coastal marshes (del Hoyo et al. 1996) and swamps (Snow and Perrins 1998). Diet Its diet is strongly seasonal (del Hoyo et al. 1996) but generally includes adult and larval aquatic insects (e.g. Coleoptera, Ephemeroptera, Trichoptera, Hemiptera, Odonata, Diptera, Neuroptera and Lepidoptera), molluscs, crustaceans, spiders, oligochaete and polychaete worms, tadpoles (del Hoyo et al. 1996) and amphibian spawn (Urban et al. 1986), small fish, fish eggs (del Hoyo et al. 1996) and occasionally seeds (Urban et al. 1986). Breeding site The nest is a depression (Flint et al. 1984) or shallow scrape positioned on hard ground near water on a hummock (Flint et al. 1984) or amongst grass and sedge (del Hoyo et al. 1996). Alternatively the nest may be a more elaborate platform of vegetation (Snow and Perrins 1998) constructed on a floating mass of aquatic vegetation (del Hoyo et al. 1996). The species nests singly or in loose colonies (del Hoyo et al. 1996), showing a preference for open areas close to foraging sites with good all-round (360 degree) visibility (Johnsgard 1981).