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 is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds 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.
The population trend is difficult to determine because of uncertainty over the extent of threats to the species (del Hoyo et al. 1996).
Behaviour This species is sedentary, although it is known to move between permanent water bodies at the height of the dry season to temporary wetlands during the rains (Hockey, et al. 2005), and to make local movements in Rwanda dependent on water levels (del Hoyo, et al. 1996). In the dry season local aggregations can occur on flooded grasslands or at contracting waters (Urban, et al. 1986) (a concentration of nearly 100 birds was recorded from Kafue Flats, SW Zambia (del Hoyo, et al. 1996), but usually flocks are smaller and of between 10 and 40 birds (Urban, et al. 1986)). When breeding however, the species disperses into single pairs on small territories (del Hoyo, et al. 1996); breeding appearing to occur all year round (del Hoyo, et al. 1996), although laying dates are likely to be at or immediately following the peak of flooding (Hockey, et al. 2005) (mainly December-March in central Africa and June-November in southern Africa) (del Hoyo, et al. 1996). Habitat This species prefers areas of stagnant water such as lakes, pools, ponds and canals, with floating vegetation (such as Salvinia molesta, Typha latifolia, Ludwigia, Cyperus, Pistia, Leersia, Oryza, Panicum repens, Vossia, Wolfia, Azolla and water-lilies Nymphaea) (Urban, et al. 1986). It can also be found on marshes, swamps, slow-flowing rivers, grass-covered floodplains, water meadows and flooded rice fields (Urban, et al. 1986, del Hoyo, et al. 1996, Hockey, et al. 2005). The species is present on both eutrophic and oligotrophic waters up to 2,200 m in Kenya, but is not found on carbonate lakes (Lewis and Pomeroy 1989). It feeds mainly on the surface of floating vegetation rather like Jacanas (Jacanidae), supported by its long toes (del Hoyo, et al. 1996), but in the dry season it also feeds on exposed mud at the edges of ponds and small gravelly waterways (Urban, et al. 1986, Hockey, et al. 2005). Diet It is carnivorous, feeding mainly on aquatic insects, maggot-like insect larvae, dragonfly nymphs, beetles, ants and small snails (Urban, et al. 1986, del Hoyo, et al. 1996). Breeding site The nest of this species varies with the habitat: it can be a shallow scrape in the mud up to 100 m from the water's edge, a shallow depression in short grass near water, a cup made from plant material on floating vegetation, or a 5-10 cm high platform of vegetation in swampy areas (Urban, et al. 1986, del Hoyo, et al. 1996).
Utilisation The species is hunted and traded at traditional medicine markets in Nigeria (Nikolaus 2001).
Text account compilers
Ekstrom, J., Butchart, S., Malpas, L.
BirdLife International (2023) Species factsheet: Vanellus crassirostris. Downloaded from http://www.birdlife.org on 21/03/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/03/2023.