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 extremely 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.4,295,000-6,800,000 individuals (Wetlands International 2015). The European population is estimated at 426,000-562,000 pairs, which equates to 853,000-1,120,000 mature individuals (BirdLife International 2015). National population estimates include: < c.10,000 individuals on migration and > c.10,000 wintering individuals in China; > c.1,000 individuals on migration and > c.1,000 wintering individuals in Taiwan; > c.1,000 individuals on migration and c.50-1,000 wintering individuals in Korea; > c.1,000 individuals on migration and c.50-10,000 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 population is therefore placed in the band 4,300,000-6,799,999 individuals.
The overall population trend is decreasing, although some populations are stable or have unknown trends (Wetlands International 2015). This species has had stable population trends over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007). The European population size trend is unknown (BirdLife International 2015).
Behaviour This species is a fully migratory circumpolar breeder with several sub-populations that employ a number of migration strategies, from short coastal flights to long, non-stop flights overland on a broad front (del Hoyo et al. 1996). The sub-population that breeds in north-east Greenland migrates through Iceland, Britain and western France to arrive in its West African wintering grounds (specifically Banc d'Arguin in Mauritania) from late-July, returning again between March and early-April (del Hoyo et al. 1996). European birds may gather in large congregations from the beginning of July in areas such as the Wadden Sea or the Wash to moult (del Hoyo et al. 1996), and some juveniles may remain in the non-breeding range all year (del Hoyo et al. 1996). The species breeds dispersed or aggregated in loose colonies, and travels in group sizes of up to 1,500 on passage, remaining in large groups (up to hundreds of thousands of birds) throughout the non-breeding season (Cramp and Simmons 1977, del Hoyo et al. 1996). The species is active both diurnally and nocturnally (Cramp and Simmons 1977, del Hoyo et al. 1996, Shepherd and Lank 2004). Habitat Breeding In the breeding season this species frequents moist boggy ground interspersed with surface water, such as tussock tundra and peat-hummock tundra in the arctic, as well as wet coastal grasslands, salt marshes and wet upland moorland (Cramp and Simmons 1977, del Hoyo et al. 1996). Non-breeding In the non-breeding season this species mainly prefer estuarine mudflats, but also frequent a wide variety of freshwater and brackish wetlands (Cramp and Simmons 1977, del Hoyo et al. 1996), both coastal and inland, including lagoons, muddy freshwater shores, tidal rivers, flooded fields, sewage farms, salt-works, sandy coasts (Cramp and Simmons 1977, del Hoyo et al. 1996), lakes and dams (Hockey et al. 2005). For roosting during high tides and at night this species prefers large fields of naturally fertilised short pasture or soil-based crops with few vertical structures that could be used by predators (Shepherd and Lank 2004). Diet Breeding This species is omnivorous during the breeding season, consuming mostly adult and larval insects (dipteran flies, beetles, caddisflies, wasps, sawflies and mayflies), and also spiders, mites, earthworms, snails, slugs and plant matter (usually seeds) (Cramp and Simmons 1977, del Hoyo et al. 1996). Non-breeding It is also omnivorous during the non-breeding season, consuming mostly polychaete worms and small gastropods, as well as insects (dipteran flies and beetles), crustaceans, bivalves, plant matter and occasionally small fish (Cramp and Simmons 1977, del Hoyo et al. 1996). Breeding site Its nest is a scrape or shallow depression in the ground, concealed in vegetation and sometimes in a tuft or tussock (and thus raised slightly off the ground) (Cramp and Simmons 1977, del Hoyo et al. 1996). Management information The provision of well-surfaced paths in breeding areas that recieve > 30 visitors a day has been shown to reduce the impact of human disturbance on this species' reproductive performance (Pearce-Higgins et al. 2007). It is also known to show increased hatching successes when ground predators have been excluded by erecting protective fences around nesting areas (Jackson 2001).
Breeding This species is significantly threatened by the loss of its breeding habitat though afforestation of moorland (del Hoyo et al. 1996, Lavers and Haines-Young 1997). It may also suffer from nest predation by introduced mammals (e.g. European hedgehog Erinaceus europeaus) on some islands (Jackson 2001). Non-breeding In the winter this species is restricted to a small number of estuaries, so it is vulnerable to any changes in this habitat for example through land reclamation (drainage) (del Hoyo et al. 1996), and the invasion of alien plant species (such as the grass Spartina anglica which has spread on British mudflats, resulting in the reduction in size of feeding areas available) (del Hoyo et al. 1996). The species is also threatened by disturbance on intertidal mudflats from construction work (UK) (Burton et al. 2002a) and foot-traffic on footpaths (Burton et al. 2002b). Important migratory stop-over habitats on the Baltic Sea coastline adjacent to the Kaliningrad region of Russia are threatened by petroleum pollution, wetland drainage for irrigation, peat-extraction, reedbed mowing and burning, and abandonment and changing land management practices leading to scrub and reed overgrowth (Grishanov 2006). The species is also susceptible to avian influenza (strain H5N1 in particular) and is therefore threatened by outbreaks of the virus (Melville and Shortridge 2006).
Conservation Actions Underway
The species is listed on Annex I of the EU Birds Directive and Annex II of the Bern Convention.
Conservation Actions Proposed
The following information refers to the species's European range only: The provision of well-surfaced paths in breeding areas that receive > 30 visitors a day has been shown to reduce the impact of human disturbance on this species's reproductive performance (Pearce-Higgins et al. 2007). It is also known to show increased hatching success when ground predators have been excluded by erecting protective fences around nesting areas (Jackson 2001). Recreation, pollution of wetland habitats, drainage and afforestation of wetland areas at key breeding and staging areas should be controlled.
Text account compilers
Butchart, S., Ekstrom, J., Jones, V., Ashpole, J, Malpas, L.
BirdLife International (2020) Species factsheet: Calidris alpina. Downloaded from http://www.birdlife.org on 23/01/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/01/2020.