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 threshold for Vulnerable under the population trend criterion (>30% decline over ten years of 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 population is suspected to be in the range 25,000-100,000 individuals (Wetlands International 2018).
The species is tentatively assessed as being in decline due to habitat loss per Tracewski et al. (2016).
Behaviour The movements of this species are very little known (del Hoyo et al. 1992), although it appears to be sedentary, possibly making partial seasonal migrations related to the onset of the rains (del Hoyo et al. 1992, Kushlan and Hancock 2005). It breeds in solitary pairs (del Hoyo et al. 1992), the breeding season varying geographically, but usually coinciding with the rains or the early dry season when floods are at their highest (Brown et al. 1982, del Hoyo et al. 1992, Kushlan and Hancock 2005). The species feeds singly or in pairs and is strictly nocturnal (Brown et al. 1982, del Hoyo et al. 1992), requiring secure day-roosting spots such as high trees or very dense marsh and forest vegetation (Kushlan and Hancock 2005). Habitat The species inhabits densely vegetated forest (Kushlan and Hancock 2005), frequenting tree-fringed streams, mangroves, islands in large rivers and lakes, the wooded margins of marshes (del Hoyo et al. 1992, Hockey et al. 2005) and occasionally reedbeds (del Hoyo et al. 1992). Diet Its diet is little known, but may consist of small fish, amphibians, molluscs, crustaceans, flying ants, flies and other insects (del Hoyo et al. 1992). Breeding site The nest is a stick platform (Hockey et al. 2005), usually well hidden and built low over water in trees or bushes (Hockey et al. 2005), occasionally away from water in trees, bushes, reedbeds, mangroves, or on rocks, rock piles on islands (Hockey et al. 2005, Kushlan and Hancock 2005) or rocky shores in caves (Kushlan and Hancock 2005), but very rarely in exposed positions (Hockey et al. 2005).
The species is threatened in southern Africa by habitat loss and degradation. Overgrazing, increased water offtake, soil erosion and poor river management are leading to siltation, reduced river flows, and increased water turbidity, and riparian vegetation is being cleared for agriculture (del Hoyo et al. 1992, Barnes 2000). Utilisation This species is hunted and traded at traditional medicine markets in Nigeria (Nikolaus 2001).
Text account compilers
Hermes, C., Ekstrom, J., Malpas, L., Palmer-Newton, A., Butchart, S.
BirdLife International (2019) Species factsheet: Calherodius leuconotus. Downloaded from http://www.birdlife.org on 23/04/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/04/2019.