Habitat and Ecology
Habitat and Ecology
Behaviour In temperate regions breeding populations of this species are sedentary or dispersive, often making local movements during severe weather5. Other populations are fully migratory2 with females and juveniles leaving the breeding grounds in the western Palearctic from Septemberand returning as early as February5. The species breeds between March and June3 in single pairs or loose groups1 although the exact timing varies with latitude3. While the females are incubating4 (from mid-May)5, 6 the males gather3 in small flocks and migrate to moulting areas6 where they undergo a flightless moulting period lasting for c.4 weeks5 (females moult near the breeding grounds)6. Outside of the breeding season the species can be found in small to very large flocks3 numbering up to several hundreds or even thousands of individuals7 especially when moulting5, on migration7 and during the winter2. The species may also roost both nocturnally and diurnally in communal groups when not breeding8. Habitat The species occurs in almost every wetland type1 although it generally avoids fast-flowing, oligotrophic1, 5, 7, deep, exposed, rough, rockbound waters and hard unvegetated areas such as rocky ground, sand dunes and artificial surfacing7. It requires water less than 1 m deep for foraging7 and shows a preference for freshwater habitats3 although it may frequent shallow brackish waters as long as they provide the cover1, 5 of submerged, floating, emergent or riparian vegetation, dense reedbeds or overhanging branches7. Habitats commonly frequented include flooded swampy woodlands, seasonal floodlands7, wet grassy swamps and meadows, oxbow lakes6, open waters with mudflats, banks or spits, irrigation networks, reservoirs, ornamental waters1, 5, 7, canals and sewage farms7. During the winter the species may also be found in saline habitats along the coast3 where water is shallow, fairly sheltered and within site of land7 (e.g. brackish lagoons7, brackish estuaries1, 7 and bays1). Diet The species is omnivorous and opportunistic1, 7, feeding by dabbling in water and by grazing on the land7. Its diet consists of seeds and the vegetative parts of aquatic and terrestrial plants (e.g. crops)1, as well as terrestrial and aquatic invertebrates (especially in the spring and summer) such as insects, molluscs, crustaceans, worms and occasionally amphibians and fish1. Breeding site The nest is a shallow depression7 or bowl of vegetation that can be situated in many different locations such as within vegetation on the ground, in natural tree cavities1 up to 10 m high (Africa)8, under fallen dead wood, on tree stumps6, under bushes8 and even in abandoned nests of other species (e.g. herons or crows)6. Nests are generally placed close to water2 although occasionally they may be some distance away3. Management information "Extensive" grazing of wetland grasslands (c.0.5 cows per hectare) was found to attract a higher abundance of the species in Hungary19. Studies in Danish coastal wetlands found that the spatial restriction of shore-based shooting was more successful at maintaining waterfowl population sizes than was the temporal restriction of shooting, and therefore that wildfowl reserves should incorporate shooting-free refuges that include adjacent marshland in order to ensure high waterfowl species diversity20. The cyclical removal of adult fish from an artificial waterbody (gravel pit) in the UK resulted in an increase in invertebrate food availability and an increase in the growth of submerged aquatic macrophytes, which in turn led to an increased use of the habitat for brood rearing by the species26. The removed fish (dead or alive) were sold to generate funds26. The species will also nest in artificial nest boxes1, 8.
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