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 very 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 (Boddaert, 1783)

Taxonomic source(s) Dowsett and Forbes-Watson (1993), Sibley and Monroe (1990, 1993)

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

110,000 - 270,000

unset

17,800,000 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 somewhat nomadic³ or partially migratory⁶, making local dry-season movements dictated by habitat and water availability^{1, 3} or dispersing to favoured moulting areas⁵. The timing of the breeding season varies geographically¹ but may be triggered by the rains². The species usually nests in solitary pairs^{1, 6} but is commonly found in small family groups outside of the breeding season^{3, 6}, large concentrations of 10 to 200 individuals⁵ also forming during the dry season or at moulting sites³. Habitat The species inhabits permanent or temporary³ swamps, marshes, inland deltas (e.g. the Okavango), shallow lakes¹, pools³, farm impoundments, flood-plains⁶, slow-flowing rivers¹ and occasionally coastal lagoons³. It shows a preference for deep¹ clear waters⁵ with abundant emergent and aquatic vegetation³, especially water-lilies (Nymphaea spp.)¹. Diet Its diet consists predominantly of the seeds of water-lilies (Nymphaea spp.)¹, although the seeds and vegetative parts of other aquatic plants¹ (e.g. pondweeds Potamogeton spp.)⁶, aquatic insects and small fish may also be taken¹. Breeding site The species nests in natural hollows or the disused holes of barbets Megalima spp. and woodpeckers in trees², preferably those standing in or close to water². It may also nest in other cavities¹ such as holes in cliffs or termites mounds³, in the disused nests of Hamerkop Scopus umbretta², or in ground sites such as papyrus stands² or grass clumps⁵. Elevated nests are usually up to 10 m⁵ (occasionally 20 m) above the ground⁴. The species will also nest in artificially erected nest boxes⁶. Management information In South Africa a breeding pair successfully nested in an artificial nest-log (a stem of Euphorbia ingens) measuring 60 x 21 cm with a horizontal oval entrance-hole measuring 7 x 8 cm and an internal cavity diameter of 12 cm that was fixed to a tree 4.2 m above the ground at the edge of water⁵.

Threats The species has declined is Madagascar as a result of hunting¹. It is also threatened by habitat degradation such as the destruction of aquatic plant communities through the introduction of exotic fish (e.g. cichlids Tilapia spp.), siltation, pollution (e.g. herbicides), drainage and tourist water-sports (which destroy lily beds)².

References 1. del Hoyo et al. (1992). 2. Kear (2005b). 3. Madge and Burn (1988). 4. Johnsgard (1978). 5. Brown et al. (1982). 6. Hockey et al. (2005).

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: Nettapus auritus. 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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