Calidris tenuirostris


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Calidris tenuirostris
Species Authority: (Horsfield, 1821)
Common Name(s):
English Great Knot
French Bécasseau d'Anadyr
Taxonomic Notes:

Assessment Information [top]

Red List Category & Criteria: Vulnerable A4bcd ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Amano, H., Clemens, R., Moores, N., Rogers, D., Crockford, N. & Allen, D.
Facilitator/Compiler(s): Butchart, S., Calvert, R., Derhé, M., Ekstrom, J., Malpas, L.
This species is classified as Vulnerable owing to a rapid population decline caused by the reclamation of non-breeding stopover grounds, and under the assumption that further proposed reclamation projects will cause additional declines in the future.

Geographic Range [top]

Range Description: Calidris tenuirostris breeds in north-east Siberia, Russia, wintering mainly in Australia, but also throughout the coastline of South-East Asia and on the coasts of India, Bangladesh, Pakistan, and the eastern coast of the Arabian Peninsula (del Hoyo et al. 1996). The Yellow Sea of North Korea, South Korea and China is a particularly important stop-over site on migration in both spring and autumn. The global population has been estimated at 380,000 individuals, of which 176,000 were thought to pass through South Korea (Wetlands International 2006). Since then the reclamation and development of wetlands in South Korea has led to a decline in the observed counts of non-breeding populations, mostly notably including dramatic declines at the Saemangeum wetland which previously held c.20-30% of the global population on migration (Moores in litt. 2009, Rogers et al. in litt. 2009). Despite there being no observed declines within the Chinese portion of the Yellow Sea, further declines at smaller staging grounds in Japan and at major wintering grounds in Australia (of c.90,000 individuals [Rogers et al. 2009]) make it clear that the population is declining overall (Amano 2006, Moores et al. 2008, R. Clemens in litt. 2010).

Australia; Bangladesh; Brunei Darussalam; China; Guam; Hong Kong; India; Indonesia; Iran, Islamic Republic of; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Kuwait; Malaysia; Micronesia, Federated States of ; Myanmar; Northern Mariana Islands; Oman; Pakistan; Palau; Papua New Guinea; Philippines; Russian Federation; Saudi Arabia; Singapore; Sri Lanka; Taiwan, Province of China; Thailand; Timor-Leste; United Arab Emirates; Viet Nam
Bahrain; Denmark; Djibouti; Germany; Ireland; Israel; Mauritius; Morocco; Netherlands; New Caledonia; New Zealand; Norway; Qatar; Seychelles; Spain; United Kingdom; United States; Yemen
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The global population has been estimated to number c.380,000 individuals (Wetlands International, 2006). Following the reclamation of the tidal flats at Saemanguem, c.90,000 non-breeding individuals disappeared from the area. Surveys elsewhere in South Korea confirmed they had not been displaced, and a decline of the same magnitude and timing in Australia suggests that individuals previously using Saemanguem have died (D. Rogers in litt. 2009). Therefore a global population of c.290,000 individuals is estimated, though given documented declines elsewhere the true figure is likely to be lower. National population estimates include: < c.10,000 individuals on migration and < c.1,000 wintering individuals in China; c.1,000-10,000 individuals on migration and < c.50 wintering individuals in Taiwan; c.50-10,000 individuals on migration in Japan and c.10,000-100,000 breeding pairs and > c.10,000 individuals on migration in Russia (Brazil 2009).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Behaviour This species is a long-distance migrant that largely travels along the coast making few stopovers (del Hoyo et al. 1996) but utilising different routes in the autumn and the spring (del Hoyo et al. 1996, Higgins and Davies 1996). It breeds from late-May to late-June, departing the breeding grounds in July and arriving on the wintering grounds between August and October (del Hoyo et al. 1996). The return migration to the breeding grounds takes place from March to April (del Hoyo et al. 1996) although juvenile non-breeders often remain in the tropical parts of the wintering range for the breeding season (Hayman et al. 1986). The species forages in large flocks of one hundred to several thousand (del Hoyo et al. 1996) at favoured sites on passage (Hayman et al. 1986), but during the winter it typically forages in small groups (Johnsgard 1981). Habitat Breeding The species breeds on gravelly areas covered with lichen and patches of herbs, heather (del Hoyo et al. 1996), Empetrum spp., Dryas spp. and Vaccinium spp.(Johnsgard 1981), or alternatively on areas with a continuous layer of lichen and scattered stunted larch Larix spp. or dwarf pine Pinus pumila (del Hoyo et al. 1996). It occurs on plateaus or gentle slopes with montane tundra in the subarctic at heights of 300-1,600 m (del Hoyo et al. 1996). Non-breeding In its wintering range the species occurs in sheltered coastal habitats such as inlets, bays, harbours, estuaries and lagoons with large intertidal mud and sandflats, oceanic sandy beaches with nearby mudflats (del Hoyo et al. 1996, Higgins and Davies 1996), sandy spits and islets, muddy shorelines with mangroves and occasionally exposed reefs or rock platforms (Higgins and Davies 1996). It roosts in refuges (Rogers et al. 2006) such as shallow water in sheltered sites, on coastal dunes or on saltflats amongst mangroves (Higgins and Davies 1996) during high tides (Rogers et al. 2006). On passage the species stages in estuaries and on intertidal mudflats (Tomkovich 1997, Moores 2006). Diet Breeding The adult breeding diet consists predominantly of plant material such as berries (del Hoyo et al. 1996) (e.g. of Empetrum nigrum) (Johnsgard 1981) and pine kernels of dwarf pine Pinus pumilla (del Hoyo et al. 1996). Small chicks feed exclusively on insects (e.g. larval Diptera and Coleoptera) and spiders (del Hoyo et al. 1996). Non-breeding During the winter and on passage the species takes bivalves up to 36 mm long from intertidal mudflats as well as gastropods, crustaceans (del Hoyo et al. 1996) (e.g. crabs and shrimps) (Higgins and Davies 1996), annelid worms and echinoderms (e.g. sea cucumbers) (del Hoyo et al. 1996). Breeding site The nest may be an open depression in moss (Flint et al. 1984) but very few nests have been found (Johnsgard 1981).

Systems: Terrestrial; Marine

Threats [top]

Major Threat(s): In the Chinese, North Korean and South Korean regions of the Yellow Sea (a major stopover area) the species is threatened by the degradation and loss of wetland habitats through environmental pollution (Kelin and Qiang 2006) (e.g. oil contamination of intertidal mudflats) (Tomkovich 1997), reduced river flows and human disturbance (Kelin and Qiang 2006) (e.g. from off-road vehicles, tourists and hunters) (Tomkovich 1997). In South Korea, after the loss of the important Saemangeum stopover area and almost all of the tidal-flats in Asan Bay and much of Namyang bay, possibly only five sites nationwide remain internationally important. Of these, only one (the Geum Estuary) currently has a low risk of reclamation, with the other four at risk due to the construction of tidal power plants and barrages, industrial use and urban expansion (Moores in litt. 2009). The species is also potentially threatened by climate change because it has a geographically bounded distribution: its global distribution is restricted to within c.10o latitude from the polar edge of continent and within which 20-50% of current vegetation type is projected to disappear under doubling of CO2 levels (BirdLife International unpublished data).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
No specific conservation action is known for this species, although population trends are being monitored in Australia as part of the Monitoring Yellow Sea Migrants in Australia project.

Conservation Actions Proposed
Identify key stopover areas and prevent their reclamation. Continue to monitor population trends. Restore reclaimed wetland sites. Campaign to stop shorebird hunting in Asian countries. Legally protect it in all range states. Survey the breeding grounds for potential threats. Manage roost sites in the species's Australian wintering range to minimise disturbance (Rogers et al. 2006).

Citation: BirdLife International 2012. Calidris tenuirostris. The IUCN Red List of Threatened Species. Version 2015.2. <>. Downloaded on 04 September 2015.
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