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).