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 thresholds for Vulnerable 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.
Although Wetlands International consider the current population trend to be unknown, it is suspected to be decreasing due to habitat loss and degradation and perhaps also hunting pressure (del Hoyo et al. 1996).
Behaviour This species is a intra-African migrant (Urban et al. 1986, del Hoyo et al. 1998, Hockey et al. 2005), undertaking post-breeding (del Hoyo et al. 1998) seasonal movements in relation to water level changes (departing when an area becomes flooded (Urban et al. 1986) and arriving when bare rocks are exposed by drought (Hockey et al. 2005)). It breeds during the dry season (Urban et al. 1986, del Hoyo et al. 1998) in small, loose colonies of up to 26 pairs (del Hoyo et al. 1998, Hockey et al. 2005), and often with many attendant non-breeders (Hockey et al. 2005). The species is strongly gregarious even when not breeding (Urban et al. 1986, del Hoyo et al. 1998) and is commonly found in groups of 2-10 (Urban et al. 1986), sometimes gathering in flocks of more than 100 individuals prior to migration (Hockey et al. 2005). It is mainly crepuscular, foraging on the wing at dawn and dusk (del Hoyo et al. 1998). Habitat This species shows a preference for exposed emergent rocks in large rivers and streams (Hayman et al. 1986, del Hoyo et al. 1998), sometimes also frequenting mud and sandbars by lagoons (Urban et al. 1986), dams and ponds on migration (Hockey et al. 2005). When rivers flood it may move to coastal areas, or other inland waters (del Hoyo et al. 1998). Diet This species is insectivorous, its diet consisting chiefly of flies (including tsetse flies Glossina), ants, beetles (del Hoyo et al. 1998), moths, grasshoppers, leaf cicadas and termite alates (Hockey et al. 2005). Breeding site Eggs are laid directly into shallow depressions, cracks, and on the flat tops of bare rocks (Urban et al. 1986, del Hoyo et al. 1998) surrounded by deep and sometimes fast-flowing water (Hayman et al. 1986), or on rock ledges and under overhangings (Hockey et al. 2005). Most nests are found within a metre or two of the water level (Harrison et al. 1997).
This species is threatened by dam construction (Irwin 1981, Harrison et al. 1997, Hockey et al. 2005)as it is vulnerable to the fluctuating water levels of dammed rivers, and the loss of suitable habitat through the creation of lakes (Irwin 1981, Williams et al. 1989, Harrison et al. 1997, del Hoyo et al. 1998, Hockey et al. 2005). Destruction of the species' riverine rocky habitat has occurred in southern Africa through extensive siltation of the southeastern lowveld rivers (Harrison et al. 1997). Utilisation Nestlings and eggs may be gathered for human use from breeding areas along the Zambezi River (Williams et al. 1989).
Text account compilers
Ekstrom, J., Butchart, S., Malpas, L.
BirdLife International (2021) Species factsheet: Glareola nuchalis. Downloaded from http://www.birdlife.org on 18/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/10/2021.