Justification of Red List Category
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 may be moderately small to large, but it is not believed to 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.
The overall population trend is decreasing, although some populations may be stable and others have unknown trends (Wetlands International 2006).
Behaviour It is not a migrant, being territorial and sedentary within a permanent range (Scott and Rose 1996), although in South Africa some birds move from rivers to large local open waters to roost, returning to the rivers in the early morning (Scott and Rose 1996). This species breeds irregularly, the timing of breeding varying with locality (del Hoyo, et al. 1992), and throughout both breeding and non-breeding seasons the species remains dispersed as individuals or single pairs (Kear 2005b). It does not form large aggregations (Kear 2005b), although roosting flocks may be large (Brown, et al. 1982). Adults undergo a flightless moulting period lasting around 25-30 days; males moulting between October and February (numbers peaking in November), females between November and February (numbers peaking in December) (Hockey, et al. 2005). The species is diurnal, usually resting at night and spending daylight hours feeding, sleeping and preening (Brown, et al. 1982). Habitat This species prefers fast-flowing shallow rivers and streams with rocky substrates, particularly in wooded and mountainous country (Johnsgard 1978, Hockey, et al. 2005) up to 4,250 m (Scott and Rose 1996). It can also be found in open, arid habitats and on lakes, reservoirs, lagoons, sandy-bottomed estuaries, stagnant or slow-flowing water (Johnsgard 1978, Brown, et al. 1982), and sewage ponds (Hockey, et al. 2005). During this species' flightless moult period it requires cover near its foraging areas (e.g. lodged branches or undercut banks) (Hockey, et al. 2005). Diet It has an omnivorous diet consisting of waterweeds and other aquatic vegetation, agricultural grain (Johnsgard 1978, Hockey, et al. 2005), fruits from terrestrial plants overhanging the water, mulberries (Morus), firethorn (Pryacantha) berries, fallen acorns (Hockey, et al. 2005), aquatic insects and their larvae, crustaceans, larval amphibians and fish spawn (Johnsgard 1978, Hockey, et al. 2005). Breeding site Ground cavity nests and elevated tree-nesting sites have been reported for this species, but usually nests are sited close to running water on islands, grassy river banks, in reedbeds or amongst driftwood (Johnsgard 1978). Important criteria for suitable nest sites are close proximity to water and near invisibility from above (Johnsgard 1978).
The species is threatened by deforestation in Kenya (del Hoyo, et al. 1992), and as it is a river specialist it is vulnerable to habitat loss through river degradation (Hockey, et al. 2005) such as dam building, water extraction (Hockey, et al. 2005, Kear 2005b), siltation, pollution, clearing of riparian vegetation and alien biota (Hockey, et al. 2005). Hybridisation of the species with Mallard Anas platyrhynchos is also a potential threat (Hockey, et al. 2005).
Text account compilers
Butchart, S., Malpas, L., Ekstrom, J.
BirdLife International (2021) Species factsheet: Anas sparsa. Downloaded from http://www.birdlife.org on 16/01/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/01/2021.