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)

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

5,300,000 - 5,400,000

unset

28,400,000 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 strongly migratory throughout its northern range^{1, 2} although some populations in the Southern Hemisphere are sedentary¹. It breeds in solitary pairs or loose groups¹ from April to June³, with males leaving the breeding areas first from May to early-June to undertake extensive moult migrations (females following later)⁵. During moult, large sexually segregated³ flocks gather in moulting areas² (e.g. in the Netherlands and Russia), although small gatherings are also possible⁵. The flightless moult period lasts for around 4 weeks^{4, 5} between July and August⁵ after which flocks move southwards to winter quarters from mid-August onwards^{3, 5}. The species is highly gregarious in winter and on passage, often forming enormous concentrations^{3, 5} (although the size of flock depends on the size of the wetland)⁷. It feeds nocturnally^{6, 8}, flocks roosting by day on open water⁶. Habitat The species shows a preference for open lowland grassland⁷, prairie or tundra habitats⁴ containing freshwater, brackish and saline wetlands with shallow water (10-30 cm deep⁷) to facilitate dabbling². Wetland habitats include shallow freshwater marshes^{1, 4, 8}, small marshy lakes, slow-flowing rivers^{1, 3, 4, 8}, wet meadows³, flood-plains and sewage ponds (southern Africa)⁸, especially favouring ponds with low, dense marginal vegetation and wetlands interspersed with brushy thickets or copses⁴. During the winter it also frequents large inland lakes⁵, brackish coastal lagoons^{1, 3, 5}, brackish³ and saline marshes¹⁸, shallow fresh or brackish estuaries^{4, 6, 7}, tidal flats³ and river deltas⁵ with adjacent agricultural land (e.g. stubble fields⁷) and scattered impoundments⁴. Diet This species is omnivorous¹ and opportunistic⁴, its diet consisting of algae⁶, seeds⁸ (e.g. cereals¹ and rice⁶), tubers (e.g. potatoes)^{1, 6, 8}, and the vegetative parts of aquatic plants, sedges^{1, 8} and grasses^{6, 8}, as well as aquatic invertebrates (e.g. insects, molluscs and crustaceans), amphibians^{1, 6, 8} and small fish¹. Breeding site The nest is a slight hollow on the ground amongst vegetation¹ (e.g. rushes, grass or low scrub) and can be close to or more than 1 km away from water^{2, 7}. The species is not normally colonial but neighbours may nest as close as 2-3 m apart².

Threats The species is threatened by wetland habitat loss on its breeding and wintering grounds⁵. Reclamation of coastal areas for industrial development poses a threat in Europe, and major river diversion and irrigation schemes threaten wintering areas in Niger and Nigeria⁵. The species is also threatened by petroleum pollution, wetland drainage, peat-extraction, changing wetland management practices (decreased grazing and mowing in meadows leading to scrub over-growth) and the burning and mowing of reeds in Russia¹¹. The species suffers from over-exploitation in Europe², and is hunted for sport in North America^{9, 10}. It also suffers poisoning from lead shot ingestion in North America⁹, poisoning from white phosphorous (from firearms) ingestion in Alaska¹⁸, and 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 chain²¹. The pecies is predated by feral cats Felis catus and rats Rattus norvegicus on islands¹, and is susceptible to avian botulism¹² and avian influenza^{13, 17} so may be threatened by future outbreaks of these diseases. Utilisation The species is hunted recreationally in Denmark¹⁴ and the Po delta, Italy¹⁵, and is hunted commercially and recreationally in Iran¹⁶. The eggs of this species used to be (and possibly still are) harvested in Iceland¹⁹. The species is also traded at traditional medicine markets in Nigeria²⁰.

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. Snow and Perrins (1998). 8. Hockey et al. (2005). 9. Baldassarre and Bolen (1994). 10. Schmidt (2006). 11. Grishanov (2006). 12. Rocke (2006). 13. Melville and Shortridge (2006). 14. Bregnballe et al. (2006). 15. Sorrenti et al. (2006). 16. Balmaki and Barati (2006). 17. Gaidet et al. (2007). 18. Steele et al. (1997). 19. Gudmundsson (1979). 20. Nikolaus (2001). 21. Paveglio et al. (1997).

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 acuta. Downloaded from http://www.birdlife.org on 9/2/2010

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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