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.
The overall population trend is decreasing, although some populations have unknown trends (Wetlands International 2006).
Behaviour This species is both sedentary and partially migratory, with some populations undertaking local seasonal movements (Urban et al. 1986, del Hoyo et al. 1996). In southern and eastern Africa adults of coastal populations are sedentary (Urban et al. 1986), although they often move from exposed to sheltered shores in the winter (Hockey et al. 2005). Inland populations in central and southern Africa are partially migratory and move to the east coast when rivers flood between December and May (del Hoyo et al. 1996) (in years of poor rainfall and little flooding these populations remain inland) (Urban et al. 1986). Other populations also undergo local movements in relation to water levels (Urban et al. 1986, del Hoyo et al. 1996). During the non-breeding season this species usually remains in pairs or small flocks (Urban et al. 1986, Hockey et al. 2005), although it can be more gregarious, occasionally occurring in flocks of up to 375 individuals (Namibia) (del Hoyo et al. 1996, Hockey et al. 2005). Breeding pairs are generally solitary and territorial, although nests can be as close together as 16 m (del Hoyo et al. 1996). This species is diurnal but may forage during bright moonlit nights (del Hoyo et al. 1996). Habitat This species shows a preference for sandy seashores and coastal dunes (Urban et al. 1986), but is often found on rocky shores, coastal and inland mudflats, salt-pans, estuaries (Urban et al. 1986, del Hoyo et al. 1996), saline and brackish lagoons, and offshore islands (Johnsgard 1981). It is also occurs along sandy shores of large inland rivers and lakes (Urban et al. 1986, del Hoyo et al. 1996) (both fresh water and alkaline) (Hayman et al. 1986). Diet The species is carnivorous, feeding on insects (such as sandflies, grasshoppers, termites, mosquito pupae and fairy shrimp larvae), gastropods, bivalves, bivalve siphons, crabs and other small crustaceans, isopods and worms (Urban et al. 1986, del Hoyo et al. 1996, Hockey et al. 2005). Breeding site The nest of this species is a shallow scrape in the sand (Watson et al. 1997) usually more than 70 m above the high water mark (Watson et al. 1997, Watson et al. 1997), on dunes, sandbars, and occasionally in quarries (Urban et al. 1986, del Hoyo et al. 1996, Hockey et al. 2005) or on roadside gravel (Johnsgard 1981).
This species is potentially threatened by habitat loss through wetland destruction and degradation (Hockey et al. 2005, Wearne and Underhill 2005). A considerable contraction of the species' inland range in Zimbabwe and southern Mozambique has already occurred due to altered river morphologies as a result of dam comstruction (Hockey et al. 2005); key wetland sites in southern Africa (for example Walvis Bay, Namibia) are being degraded through wetland reclamation for suburb and port development, and changes in the flood regime due to road building (Wearne and Underhill 2005); and Ghana wetlands are under threat from coastal erosion and proposed developments involving drainage and land reclamation (Johnsgard 1981). This species is also susceptible to nest disturbance by tourists and off-road vehicles due to its preference for nesting on coastal dunes (negative impacts on nestlings in such areas have been observed) (Watson and Kerley 1995, Wearne and Underhill 2005).
Text account compilers
Ekstrom, J., Butchart, S., Malpas, L.
BirdLife International (2019) Species factsheet: Charadrius marginatus. Downloaded from http://www.birdlife.org on 20/04/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/04/2019.