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 decreasing, but it is not thought 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 global population is estimated to number c.280,000-530,000 individuals (Wetlands International 2006). The European population is estimated at 134,000-262,000 pairs, which equates to 269,000-524,000 mature individuals (BirdLife International 2015). National population estimates include: c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in China; c.100-10,000 breeding pairs, c.1,000-10,000 individuals on migration and c.1,000-10,000 wintering individuals in Taiwan; c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in Korea; c.10,000-100,000 breeding pairs, c.1,000-10,000 individuals on migration and c.50-1,000 wintering individuals in Japan and c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in Russia (Brazil 2009).
The overall population trend is decreasing, although most populations have unknown trends (Wetlands International 2015). In Europe the population size is estimated to be decreasing by less than 25% in 15 years (three generations) (BirdLife International 2015).
Behaviour This species is fully migratory in much of its range. The European and North African populations migrate across the Sahara Desert between late-July and early-September (leaving breeding grounds June to mid-July) to reach wintering grounds in tropical Africa from late-August onwards (del Hoyo et al. 1996). These population return to their breeding grounds from mid-March, where they breed April-June (Europe) or March-May (North Africa) (del Hoyo et al. 1996). Siberian and other Asian populations migrate to wintering grounds in South-East Asia and India (only crossing Japan on the northward return migration) (del Hoyo et al. 1996). Some populations in South-East Asia, India, New Guinea and the Philippines do not migrate but are sedentary or locally nomadic in response to water levels (del Hoyo et al. 1996). This species is mainly solitary throughout the non-breeding season and on migration, occasionally occurring in flocks of not more than 10 individuals (Cramp and Simmons 1983, Hayman et al. 1986, del Hoyo et al. 1996). It also breeds singly or in loose neighbourhood groups spaced 7-200 m apart (del Hoyo et al. 1996). Habitat Breeding During the breeding season this species shows a preference for bare or sparsely vegetated sandy and pebbly shores of shallow standing freshwater pools, lakes or slow-flowing rivers (Johnsgard, 1981, Cramp and Simmons 1983, del Hoyo et al. 1996, Grimmett et al. 1998), including river islands, dry, stony riverbeds, sand, shingle or silt flats (Johnsgard 1981, del Hoyo et al. 1996), dry wadis and dune slacks (Cramp and Simmons 1983). This species may also utilise temporary artificial habitats such as gravel pits (Ratcliffe 1974, Cramp and Simmons 1983, del Hoyo et al. 1996), sewage works, industrial wastelands (Cramp and Simmons 1983, del Hoyo et al. 1996) and refuse tips (Cramp and Simmons 1983, Hayman et al. 1986), and may use open arable land on clay soil in exceptional circumstances (Johnsgard, 1981) (resident populations in India it can be found on wet grassland and rice paddy-fields) (Grimmett et al. 1998). The species prefers lowland habitats and is rarely found above 800 m in Europe (Cramp and Simmons 1983, del Hoyo et al. 1996), but where river banks, dry riverbeds, or islets offer suitable habitat it will penetrate further upstream, reaching higher than 2,000 m in Afghanistan (e.g. in the mountains of Kashmir where it occurs along the pebbly banks of fast-flowing mountain torrents) (Johnsgard 1981), and even higher in the east Palearctic (Cramp and Simmons 1983). The species generally avoids rough or broken terrain, forest, cultivated land or pastures, and tall or dense vegetation including vegetated margins of inland waters (Cramp and Simmons 1983). It is also very rarely found on the coast, although it may occasionally visit saline inland pools and flats, intertidal areas on the seashore, mudflats, tidal creeks and brackish estuaries or lagoons (in India for example) (Cramp and Simmons 1983, del Hoyo et al. 1996, Grimmett et al. 1998). Non-breeding In its African wintering grounds this species favours extensive sandbanks (Johnsgard 1981), muddy and sandy shores of rivers and lakes, residual flood waters, short grassy areas on dry ground around villages or near water, airfields and pastures (Urban et al. 1986, Hockey et al. 2005). It less commonly inhabits coastal areas such as saltpans, estuaries, creeks or rainwater pools on dry salt-flats bordering mangroves (Urban et al. 1986). The species prefers lowland habitats during the winter as well as during the breeding season and is rarely found above 800 m in its wintering range (Hockey et al. 2005). Diet The species is carnivorous, its diet consisting mainly of insects such as beetles, flies (especially larvae and pupae), ants, bugs, mayfly and dragonfly larvae, caddisflies, crickets and larval Lepidoptera, as well as spiders, freshwater shrimps and other small crustaceans, mussels, worms and snails (Johnsgard, 1981, Cramp and Simmons 1983, Urban et al. 1986, del Hoyo et al. 1996). Vegetation (such as the seeds of grasses, sedges, Polygonum and Compositae) is taken rarely and is likely to be ingested incidentally along with animal matter (Cramp and Simmons 1983). Breeding site The nest is a shallow scrape on loose sand, dry mud or on flat, bare rocks surrounded by mud or sand (Johnsgard, 1981, Urban et al. 1986), sometimes amongst sparse vegetation (del Hoyo et al. 1996, Grimmett et al. 1998) in the vicinity of water, and often on small islands (del Hoyo et al. 1996) or adjacent farmland (Hayman et al. 1986). Nesting pairs have also been recorded on flat gravelled roofs (Cramp and Simmons 1983).
This species is threatened primarily by the degradation and loss of its preferred habitats (del Hoyo et al. 1996, Barter 2002). Many of the species's breeding sites are also disturbed by human recreational activities (del Hoyo et al. 1996). Increased flood regulation and pollution from oil and tar along the Mediterranean coast and the River Jordan has resulted in the degradation of the breeding sites in those areas (del Hoyo et al. 1996). In China and South Korea important migrational staging areas around the coast of the Yellow Sea are being lost through land reclamation and degraded as a result of declining river flows (from water abstraction), increased pollution, unsustainable harvesting of benthic fauna and a reduction in the amount of sediment being carried into the area by the Yellow and Yangtze Rivers (Barter 2002, 2006). The species may also be susceptible to outbreaks of avian botulism (Hubalek et al. 2005), and is potentially at risk from exposure to DDT's in southern India (Tanabe et al. 1998).
Conservation Actions Underway
The species is listed on Annex II of the Bern Convention.
Conservation Actions Proposed
The following information refers to the species's European range only: Recreation at breeding sites needs to be controlled.
Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J., Malpas, L.
BirdLife International (2018) Species factsheet: Charadrius dubius. Downloaded from http://www.birdlife.org on 20/06/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/06/2018.