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). The population trend appears to be stable, 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 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 stable, although some populations have unknown trends (Wetlands International 2006).
Behaviour The migratory patterns of this species are poorly known (Hancock et al. 1992, del Hoyo et al. 1992), although it is likely to make nomadic movements in response to local rainfall rather than truly seasonal movements (Hancock et al. 1992). The breeding season varies throughout the range, and is also variable from year to year, being suspended in sites when the rains do not occur (Hancock et al. 1992). The species breeds during the dry season from West Africa to eastern Sudan, in the rains (or sometimes in the dry season) in East and central Africa, and in winter or early spring in southern Africa (Hancock et al. 1992, del Hoyo et al. 1992). It nests colonially with other species (del Hoyo et al. 1992, Hockey et al. 2005), usually in groups of 5-20 pairs (Hockey et al. 2005), and occasionally in groups of up to 250 pairs or more (del Hoyo et al. 1992). It remains gregarious outside of the breeding season, usually in small parties of 3-30 individuals (Brown et al. 1982, Hockey et al. 2005), roosting communally in trees or reedbeds (Hockey et al. 2005) and resting along the shores of inland shallow waters, sometimes in large numbers of up to 1000 (Brown et al. 1982). Habitat The species inhabits large, shallow inland waters such as lakes and rivers, seasonal and permanent pans, marshes, flood plains, sewage works (Hockey et al. 2005), reservoirs and artificial ponds (Hancock et al. 1992), less often occurring at coastal lagoons, salt-pans, creeks and estuaries (del Hoyo et al. 1992). Diet The species is carnivorous, its diet consisting of small fish and aquatic invertebrates (del Hoyo et al. 1992) such as crayfish and water beetles (Hancock et al. 1992). Breeding site The nest is a flat oval platform of sticks and reeds situated over water on partly submerged trees, in bushes or reeds, on the ground on rocky islets (Brown et al. 1982, del Hoyo et al. 1992) or on rocky ledges (Hancock et al. 1992). The species nests colonially in favoured nesting sites such as secluded lakes, river oxbows and islands of vegetation (Hockey et al. 2005).
In Madagascar the species is seriously threatened by the destruction of breeding colonies at Lake Kinkony, Lake Bemamba, Lake Ihotry and Lake Alaotra (del Hoyo et al. 1992). It is also threatened by the drainage of wetlands in some areas (Hancock et al. 1992).
Text account compilers
Ekstrom, J., Butchart, S.
BirdLife International (2019) Species factsheet: Platalea alba. Downloaded from http://www.birdlife.org on 25/06/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/06/2019.