Justification This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Family/Sub-family Anatidae

Species name author Linnaeus, 1758

Taxonomic source(s) AERC TAC (2003), AOU checklist (1998 + supplements), Christidis and Boles (1994), Cramp and Simmons (1977-1994), Dowsett and Forbes-Watson (1993), SACC (2005 + updates), Sibley and Monroe (1990, 1993), Stotz et al. (1996), Turbott (1990)

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

5,500,000 - 6,000,000

unset

27,200,000 km²

No

Important Bird Areas Click here to view map showing IBAs where species is recorded and triggers any of the IBA criteria.

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 parties^{3, 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 country^{1, 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 lagoons^{1, 2, 3}, tidal muflats^{1, 2}, estuaries³, coastal shorelines⁴, fresh and brackish estuarine marshes⁴, inland seas and brackish or saline inland waters⁸, occasionally occurring (briefly) on marine waters during migration^{3, 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.

Threats The species is threatened by habitat loss in Britain and Ireland², is occasionally killed by collisions with power transmission lines²³, and suffers from nest predation by American mink Neovison vison^{17, 19, 24}. It is susceptible to avian influenza^{10, 21} and avian botulism¹⁸ so may be threatened by future outbreaks of these diseases. The species may suffer from reproductive impairment as a result of selenium (Se) accumulation in liver tissues (selenium contained in sub-surface agricultural drain-water used for wetland management in California led to bioaccumulation of the element in the food chain)²². The species suffers mortality as a result of lead shot ingestion (Camargue, France¹⁵ and Spain²⁰). Utilisation The species is a favoured quarry species throughout most of the world, but is rarely taken in large numbers². It is hunted for sport in North America⁹, Denmark¹² and the Po delta, Italy¹³, and is hunted commercially and recreationally in Iran¹⁴. The eggs of this species used to be (and possibly still are) harvested in Iceland¹⁶.

References 1. del Hoyo et al. (1992). 2. Kear (2005b). 3. Madge and Burn (1988). 4. Johnsgard (1978). 5. Scott and Rose (1996). 6. Brown et al. (1982). 7. Flint et al. (1984). 8. Snow and Perrins (1998). 9. Baldassarre and Bolen (1994). 10. Melville and Shortridge (2006). 11. Musil (2006). 12. Bregnballe et al. (2006). 13. Sorrenti et al. (2006). 14. Balmaki and Barati (2006). 15. Mondain-Monval et al. (2002). 16. Gudmundsson (1979). 17. Opermanis et al.(2001). 18. Forrester et al. (1980). 19. Bartoszewicz and Zalewski (2003). 20. Mateo et al. (1998). 21. Gaidet et al. (2007). 22. Paveglio et al. (1997). 23. Malcolm (1982). 24. Nordstrom et al. (2002). 25. Giles (1994).

Further web sources of information

Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Text account compilers Stuart Butchart (BirdLife International), Jonathan Ekstrom (BirdLife International), Lucy Malpas (BirdLife International)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Anas clypeata. Downloaded from http://www.birdlife.org on 10/2/2010

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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