White-backed Duck (Thalassornis leuconotus)

Behaviour This species is partially migratory (Scott and Rose 1996) or semi-nomadic (Kear 2005a), making local dispersive movements during the rainy season (Brown et al. 1982, Madge and Burn 1988) to take advantage of temporary wetlands (Madge and Burn 1988, del Hoyo et al. 1992). The timing of breeding varies geographically although it generally coincides with periods of higher or more stable water levels (del Hoyo et al. 1992). The species breeds in solitary pairs or loose groups (del Hoyo et al. 1992), dispersing after breeding (as water levels drop) to gather in small flocks (Kear 2005a) of 20 to 100 individuals (Brown et al. 1982) on more permanent lakes and marshes (Kear 2005a). The species is crepuscular (Kear 2005a) and obtains its food almost solely by diving (Brown et al. 1982). Habitat The species inhabits quiet shallow freshwater lakes, pools, lagoons (del Hoyo et al. 1992), pans, inland deltas (Brown et al. 1982), flood-plains (Madge and Burn 1988), marshes and swamps (del Hoyo et al. 1992) fringed with abundant emergent and floating vegetation (Brown et al. 1982, del Hoyo et al. 1992) (e.g. reeds, papyrus and water-lilies Nymphaea spp.) (Kear 2005a), generally avoiding very open water (del Hoyo et al. 1992). It also often inhabits forested lakes in Madagascar (Kear 2005a) and may frequent farm impoundments or stock-ponds in other areas (Scott and Rose 1996). Diet Although the species is predominantly herbivorous (taking the seeds and leaves of aquatic plants such as water-lilies Nymphaea spp. and Polygonum spp.) the young may feed on Chironomid insect larvae (del Hoyo et al. 1992). Breeding site The nest is constructed of vegetation either floating on or up to 45 cm above water (Brown et al. 1982) amongst reedbeds (Brown et al. 1982, del Hoyo et al. 1992) or papyrus beds (Brown et al. 1982), or on the ground in waterside vegetation on small islands (Brown et al. 1982, del Hoyo et al. 1992). The species will occasionally use the abandoned nests of grebes or coots as nest bases (Brown et al. 1982, Madge and Burn 1988).