Habitat and Ecology
Behaviour This species is highly migratory although it may be present all year round in parts of Europe1. It arrives on the breeding grounds from March3 where it breeds in solitary pairs or loose groups1 in the northern spring (chiefly from mid-April to June)3. Males undergo a post-breeding moult migration from early-May to early-June (females moulting one month later) during which they are flightless for 3-4 weeks5. The autumn migration chiefly occurs between September and October (western Europe), during which the species is likely to travel on a broad front (e.g. across Arabia and into Africa)5. The species is usually found in pairs or small parties3, 4 although it often congregates when feeding2 (flocks of 20 or 30 to several hundred individuals occur in favoured areas in Africa6 and large concentrations form at stop-over sites on migration)3. The species forages diurnally and roosts communally at night6. Habitat It inhabits permanent8 shallow freshwater wetlands1 from sea level up to 2,900 m (Ethiopia)6, preferred sites being those surrounded by dense stands of reeds or other emergent vegetation whilst being free of overhanging trees or fringing forest8. Copious submerged aquatic vegetation sheltering abundant planktonic invertebrates is a valuable habitat characteristic4. Suitable habitats include well-vegetated lakes and marshes and with muddy shores and substrates in open country1, 2, 3 (e.g. grasslands)4, 6, as well as oxbow lakes, channels and swamps (former U.S.S.R.)7. It also frequents artificial waters bordered by lush grassland8 such as sewage farms, rice-fields2 and fish ponds11. In the winter it can be found on coastal brackish lagoons1, 2, 3, tidal muflats1, 2, estuaries3, coastal shorelines4, fresh and brackish estuarine marshes4, inland seas and brackish or saline inland waters8, occasionally occurring (briefly) on marine waters during migration3, 8 (although it generally avoids very saline habitats)4. Diet Its diet consists of small aquatic invertebrates1 such as adult and larval insects1 (e.g. caddisfly larvae, damselfly and dragonfly nymphs, adult beetles, bugs4 and flies6), molluscs1, planktonic crustaceans8, the seeds1 of emergent and aquatic plants2 (e.g. bulrushes and waterweeds)4, annelids, amphibian spawn, tadpoles, spiders, fish and the vegetative parts of aquatic plants6 (e.g. duckweeds)4, 6. Breeding site The nest is a scrape2 or depression1 on the ground in tall grass, among hummocks, in the open7 or (rarely) in bulrush marshes2. Usually the species nests close to water but if grass cover is unavailable in the wetland site it may also nest far away from water under bushes7, in hayfields or in meadows2. Although it is not a colonial species, several pairs may nest in close proximity3. Management information A study in the Czech Republic found that fish ponds with a fish stock density of less than 400 kg/ha, water transparency of more than 50 cm, mixed fish stocks (e.g. tench and pike or perch) rather than monospecific stocks (e.g. of carp), and systems that include ponds with fish fry (to provide areas with low fish competition and high invertebrate availability) are more successful in supporting breeding pairs of this species11. The cyclical removal of adult fish from an artificial waterbody (gravel pit) in the UK attracted nesting pairs to the area by causing an increase in invertebrate food availability and an increase in the growth of submerged aquatic macrophytes25. The removed fish (dead or alive) were sold to generate funds25.
Systems
- Terrestrial
- Freshwater
- Marine