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). The population trend appears to be increasing, and hence the species does not 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, 1766)

Taxonomic source(s) AOU checklist (1998 + supplements), 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?

1,700,000 - 2,800,000

unset

32,700,000 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 subject to upredictable local nomadic movements⁴ (usually of less than 500 km) in relation to variations in water and food availability³. Breeding commences at the start of the local rainy season¹ with the species nesting individually^{6, 7} or in loose colonies or small groups¹. Adults undergo a post-breeding flightless moult period lasting for 18-25 days during which they are particularly vulnerable and seek the cover of densely vegetated wetlands². When not breeding the species is gregarious and may forage in flocks of up to several thousands of individuals². The species mainly forages at night¹ (although it may also feed diurnally during the winter)³. Habitat The species inhabits a wide variety of freshwater wetlands¹ including lakes, swamps², marshes, large rivers, river deltas, flood-plains³, reservoirs^{2, 3}, sewage farms (Africa)⁴ and estuaries², and is commonly encountered feeding in rice fields². It shows a preference for wetlands in open country¹ (although it is likely to inhabit fresh or brackish waters in more forested areas in South America)⁴ with mud or sandbars for roosting and rich shoreline⁴, emergent and surface vegetation⁵. Adults require densely vegetated permanent wetlands for cover during their flightless post-breeding moult period^{2, 7}, although breeding birds prefer more ephemeral wetlands⁷. Diet Its diet consists of grasses (e.g. Echinochloa spp.), aquatic seeds e.g. of water-lilies Nyphaea and Nymphoides spp., rice¹, pondweeds (e.g. Potamogeton spp.)⁷ and tubers (especially in the dry season)², as well as aquatic invertebrates such as molluscs, crustaceans and insects¹, the consumption of which is highest during the rains². Breeding site The nest is a depression⁴ or low construction of vegetation² placed over or at varying distances from water, usually in stands of dense vegetation (e.g. long grass, sedge or rice)² on dry ground or in reedbeds^{1, 4}, occasionally also in open crevices in trees (South America)^{2, 3}. The species may nest in solitary pairs^{6, 7} with nests placed more then 75 m apart (Africa)^{5, 7}, although it may also nest in loose colonies or small groups¹.

Threats The species is susceptible to avian botulism¹¹ and avian influenza¹² so may be threatened by future outbreaks of these diseases. Utilisation The species is hunted for local consumption and trade in Malawi⁸ and is hunted in Botswana¹⁰. It is also hunted and traded at traditional medicine markets in Nigeria⁹.

References 1. del Hoyo et al. (1992). 2. Kear (2005a). 3. Madge and Burn (1988). 4. Johnsgard (1978). 5. Brown et al. (1982). 6. Langrand (1990). 7. Hockey et al. (2005). 8. Bhima (2006). 9. Nikolaus (2001). 10. Herremans (1998). 11. van Heerden (1974). 12. Gaidet et al. (2007).

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: Dendrocygna viduata. 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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