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Red Knot Calidris canutus

This species has been uplisted to Near Threatened as it almost meets the requirements for listing as threatened under criteria A2abc+3bc+4abc. It has an extremely large range and six subpopulations across which trends are variable. The population trend of the largest subpopulation, islandica, is unclear as is the trend of roselaari. The rufa and canutus subpopulations have both experienced population declines. Two subpopulations use the East Asian-Australasian Flyway and have experienced significant declines owing to loss of habitat in the Yellow Sea. Should new research resolve uncertainties in the trends of several of these subpopulations the species may warrant uplisting or downlisting.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: # _the_WP15.xls#.
Christidis, L.; Boles, W. E. 2008. Systematics and taxonomy of Australian birds. CSIRO Publishing, Collingwood, Australia.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
SACC. 2006. A classification of the bird species of South America. Available at: #
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.

23-25 cm wader. Breeding adult has rich rusty chestnut underparts with blackish-pale/rufous chestnut upperparts. Female has white feathers on underpart and more white on rear belly. Non-breeding adult pale grey above with narrow white fringes on larger feathers, underparts white, with grey barring on breast and flanks (Van Gils and Wiersma 1996). Juvenile somewhat similar to non-breeding adult. Similar spp. Resembles Great Knot C. tenuirostris but larger and rump white barred grey appearing uniform grey with rest of upperparts, and white wingbar more marked.

Distribution and population
The species has an extremely large range, breeding from Alaska (U.S.A.) across the Arctic to Greenland (Denmark) and northern Russia. It winters on the Atlantic and Pacific coasts of North and South America, north-western Europe, along the west coast of Africa from Tunisia and Morocco down to South Africa, across southern Asia and around Australasia (Van Gils and Wiersma 1996). There are six subspecies: C. c. canutus breeds in central and northern Siberia, the Taymyr Peninsula and possibly Yakutia, wintering in western and southern Africa and south Asia; C. c. piersmai breeds in the New Siberian Islands (Russia) and winters in north-west Australia; C. c. rogersi breeds on the Chukotskiy Peninsula and possibly further west, and winters in Australasia; C. c. roselaari breeds on Wrangel Island (off north-east Siberia) and north-west Alaska, wintering primarily in western Mexico, as well as the coast of south-east U.S.A., southern Panama and northern Venezuela; C. c. rufa breeds in the Canadian low Arctic and winters on the coasts of south Florida, Texas, northern Brazil (15,400 individuals [R. I. G. Morrison in litt. 2015]) and southern South America; C. c. islandica breeds on the islands of the Canadian high Arctic and north Greenland, it winters in western Europe (Van Gils and Wiersma 1996). 

The main spring staging sites for each of the six subspecies have been identified: Schleswig Holstein Wadden Sea, Germany (C. c canutus); Troms and Finnmark, north Norway and west Iceland (C. c. islandica); Delaware Bay, U.S.A. (C. c. rufa); Bohai Bay, China (C. c. piersmai and C. c. rogersi) and the Yukon-Kuskokwim Delta, Copper River Delta and Grays Harbour/Willapa Bay, U.S.A. (C. c. roselaari) (Leyrer et al. 2014).

Population justification
The global population is estimated to number 891,000-979,000 individuals (Wetlands International 2015). The European population is estimated at 15,000-30,000 pairs, which equates to 30,000-60,000 mature individuals (BirdLife International 2015).

Trend justification
The islandica population trend is uncertain. According to the International Waterbird Census the short-term trend shows a moderate increase whilst the long-term trend is fluctuating (Nagy et al. 2014). However the European Red List of Birds suggests that the population is increasing strongly in the short-term and experiencing a moderate increase in the long-term (BirdLife International 2015). van Roomen et al. (2014) found the population was stable/fluctuating in the short- and long-term. The canutus population decreased strongly in the short- and long-term (2003-2014 and 1979-2014, respectively) (van Roomen et al. 2014). The roselaari population trend is uncertain, but is possibly declining (Andres et al. 2012).

The rufa population has undergone a significant decline in the last decade (Andres et al. 2012). The number of birds in Tierra del Fuego declined strongly (75% decrease) between 1985-2000 (52,244 individuals) and 2011-2013 (11,385 individuals) (USFWS 2014). Between 2010 and 2015 the population at Tierra del Fuego has varied in the range of 10,000-15,000 individuals (R. I . G. Morrison in litt. 2015). Whilst counts in Delaware Bay showed similarly large declines: 70% decrease between 1981-1983 (59,946 individuals) and 2005-2014 (18,387) (USFWS 2014). Approximately 10-14% of the global population uses the East Asian-Australasian Flyway.

An analysis of monitoring data from around Australia and New Zealand found that both the piersmai and rogersi populations which use the flyway have experienced strong population declines, estimated at a 57.4% decrease over three generations (Studds et al. in prep.). This decrease is supported by a study on adult survival. Survival in north-west Australia in late winter was constantly high however survival during periods away from Australia declined in 2011, with an annual survival rate of 0.62 (Piersma et al. submitted). The study predicts the population will halve within four years. Overall the global population is estimated to be decreasing at a rate of c. 25% in three generations.

The species breeds in the high Arctic (del Hoyo et al. 1986) on dry upland tundra including weathered sandstone ridges, upland areas with scattered willows Salix spp., Dryas spp. and poppy, moist marshy slopes and flats in foothills, well-drained slopes hummocked with Dryas spp. (Johnsgard 1981) and upland glacial gravel close to streams or ponds (del Hoyo et al. 1986). The nest is an open shallow depression (Flint et al. 1984) either positioned on hummocks surrounded by mud and water or on stony or gravelly ground (Johnsgard 1981) on open vegetated tundra or stone ridges (del Hoyo et al. 1986). Outside of the breeding season the species is strictly coastal, frequenting tidal mudflats or sandflats, sandy beaches of sheltered coasts, rocky shelves, bays, lagoons and harbours, occasionally also oceanic beaches and saltmarshes (del Hoyo et al. 1986).

During the breeding season it feeds predominantly on insects (mainly adult and larval Diptera, Lepidoptera, Trichoptera, Coleoptera and bees) as well as spiders, small crustaceans, snails and worms (del Hoyo et al. 1986). When it first arrives on the breeding grounds, however, the species is dependent upon vegetation (including the seeds of sedges, horsetails Equisetum spp. and grass shoots) owing to the initial lack of insect prey (Johnsgard 1981). Outside of the breeding season the species takes intertidal invertebrates such as bivalve and gastropod molluscs, crustaceans (del Hoyo et al.1986) (e.g. horseshoe crab Limulus spp. eggs) (Karpanty et al. 2006), annelid worms and insects, rarely also taking fish and seeds (del Hoyo et al. 1986). It is a full long-distance migrant that utilises few stopover sites or staging areas (del Hoyo et al. 1986).

The species is vulnerable to extensive land reclamation projects that encroach upon important habitat across its range (del Hoyo et al. 1986, Leyrer et al. 2014). Loss of intertidal stopover habitats due to reclamation activities in the Yellow Sea region of the East Asian-Australasian Flyway is thought to be driving declines in shorebird populations (Amano et al. 2010, Yang et al. 2011, Leyrer et al. 2014). It is estimated that up to 65% of tidal flats in the Yellow Sea region have been lost over the past five decades, with an annual loss of 1.2% per year since the 1980s (Murray et al. 2014). These losses are attributed to urban, industrial and agricultural expansion within the region. The populations of C. c. piersmai and C. c. rogersi are both threatened by reclamation projects at key staging sites in Bohai Bay, China (Leyrer et al. 2014). It is threatened by the over-exploitation of shellfish (del Hoyo et al. 1986, Goldfeder and Blanco 2006) which leads directly and indirectly to reductions in prey availability (del Hoyo et al. 1986). Damming of rivers, dredging (which reduces food availability), pollution, aquaculture operations, renewable energy developments and invasion of mudflats by Spartina grasses pose additional threats to key habitats (Leyrer et al. 2014). 

The species also suffers from disturbance in the non-breeding season as a result of tourism (Goldfeder and Blanco 2006), residential development (Leyrer et al. 2014) foot-traffic on beaches (Burton et al. 2002), recreational activities and over-flying aircraft, which together reduce the size of available foraging areas (del Hoyo et al. 1986). In the past, increased harvesting of Horseshoe Crab Limulus polyphemus in Delaware Bay, U.S.A. resulted in reduced prey availability (Leyrer et al. 2014). The species is hunted illegally for example in New Zealand (del Hoyo et al. 1986) and northern Brazil (Leyrer et al. 2014) and hunting of other species can cause disturbance and accidental mortality. C. c. islandica and C. c. canutus are both huntable in France. It is also potentially threatened by industrial pollution and oil exploration (Goldfeder and Blanco 2006), and is susceptible to avian influenza so may be threatened by future outbreaks of the virus (Melville and Shortridge 2006). Climate change induced sea level rise and thawing of permafrost pose threats to intertidal staging areas, non-breeding sites and Arctic breeding areas (Leyrer et al. 2014).

Conservation and Research Actions Underway
The species is listed on Annex II (B) of the EU Birds Directive. C. c. rufa is listed as threatened under the Endangered Species Act in the U.S.A. (Anon. 2014). In Canada C. c. canutus is listed as of Special Concern, C. c. roselaari is considered Threatened and C. c. rufa is Endangered according to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) (Anon. 2009). In 2014, five subspecies were proposed for listing for Cooperative Action under CMS (C. c. canutus, islandica, roselaari, piersmai, rogersi) (Leyrer et al. 2014). C. c. rufa is on CMS Appendix I. C. c. canutus and C. c. islandica are listed in Column B, category 2a and 2c of the AEWA Action Plan (Leyrer et al. 2014).

Conservation and Research Actions Proposed
Protect key habitat across its range and ensure that the species is legally protected in all range states (Leyrer et al. 2014). Shellfish fishing at wintering and stop-over habitats needs to be sustainably managed. Ensure sites are protected against the threats associated with oil and gas exploration. Recreation, pollution of wetland habitats, land reclamation, infrastructure development and human disturbance at key staging areas needs to be stopped. Increase awareness of the species. Expand existing monitoring schemes and conduct research into migration patterns, ecology and threats (Leyrer et al. 2014).

Related state of the world's birds case studies

Amano, T.; Szekely, T.; Koyama, K.; Amano, H.; Sutherland, W. J. 2010. A framework for monitoring the status of populations: an example from wader populations in the East Asian-Australasian flyway. Biological Conservation 143: 2238-2247.

Andres, B.A., Smith, P.A., Morrison, R.I.G., Gratto-Trevor, C.L., Brown, S.C. and Friis, C.A. 2012. Population estimates of North American shorebirds, 2012. Wader Study Group Bulletin 119(3): 178-194.

Anon. 2009. Red Knot (Calidris canutus). Status of Birds in Canada. Government of Canada / Gouvernement du Canada. Available at:

Anon. 2014. Service Protects Red Knot as Threatened Species under Endangered Species Act. Available at: (Accessed: 25/08/2015).

Beaumont, L. J.; McAllan, I. A. W.; Hughes, L. 2006. A matter of timing: changes in the first date of arrival and last date of departure of Australian migratory birds. Global Change Biology 12: 1339-1354.

BirdLife International. 2015. European Red List of Birds. Office for Official Publications of the European Communities, Luxembourg.

Brazil, M. 2009. Birds of East Asia: eastern China, Taiwan, Korea, Japan, eastern Russia. Christopher Helm, London.

Burton, N.H.K., Rehfisch, M.M. and Clark, N.A. 2002. Impacts of Disturbance from Construction Work on the Densities and Feeding Behavior of Waterbirds using the Intertidal Mudflats of Cardiff Bay, U.K. Environmental Management 30(6): 865-871.

Delany, S.; Scott, D. 2006. Waterbird population estimates. Wetlands International, Wageningen, The Netherlands.

Flint, V.E., Boehme, R.L., Kostin, Y.V. and Kuznetsov, A.A. 1984. A field guide to birds of the USSR. Princeton University Press, Princeton, New Jersey.

Goldfeder, S. D.; Blanco, D. E. 2006. The conservation status of migratory waterbirds in Argentina: towards a national strategy. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 189-194. The Stationary Office, Edinburgh, UK.

IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015-4. Available at: (Accessed: 19 November 2015).

Johnsgard, P. A. 1981. The plovers, sandpipers and snipes of the world. University of Nebraska Press, Lincoln, U.S.A. and London.

Karpanty, S. M.; Fraser, J. D.; Berkson, J.; Niles, L. J.; Dey, A.; Smith, E. P. 2006. Horseshoe Crab Eggs Determine Red Knot Distribution in Delaware Bay. Journal of Wildlife Management 70(6): 1704-1710.

Leyrer, J., van Nieuwenhove, N., Crockford, N. and Delany, S. 2014. Proposals for Concerted and Cooperative Action for Consideration by CMS COP 11, November 2014. BirdLife International and International Wader Study Group.

Melville, D. S.; Shortridge, K. F. 2006. Migratory waterbirds and avian influenza in the East Asian-Australasian Flyway with particular reference to the 2003-2004 H5N1 outbreak. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 432-438. The Stationary Office, Edinburgh, UK.

Murray, N.J., Clemens, R.S., Phinn, S.R., Possingham, H.P. and Fuller, R.A. 2014. Tracking the rapid loss of tidal wetlands in the Yellow Sea. Frontiers in Ecology and the Environment 12: 267-272.

Nagy, S., Flink, S. and Langendoen, T. 2014. Waterbird trends 1988-2012: Results of trend analyses of data from the International Waterbird Census in the African-Eurasian Flyway. Wetlands International, Ede.

Piersma, T., Lok, T., Chen, Y., Hassell, C.J., Yang, H.-Y., Boyle, A., Slaymaker, M., Chan, Y.-C., Melville, D.S., Zhang, Z.-W. and Ma, Z. Submitted. Simultaneous declines in summer survival of three shorebird species signals a flyway at risk. PLOS Biology.

Studds, C.E. et al. in prep.. Dependence on the Yellow Sea predicts population collapse in a migratory flyway.

USFWS. 2014. U.S. Fish and Wildlife Service Protects the Rufa Red Knot as Threatened Under Endangered Species Act: Questions and Answers. U.S. Fish and Wildlife Service.

Van Gils, J. and Wiersma, P. 1996. Red Knot (Calidris canutus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. and de Juana, E. (eds), Handbook of the Birds of the World Alive, Lynx Edicions, Barcelona.

Wetlands International. 2015. Waterbird Population Estimates. Available at: (Accessed: 17/09/2015).

Yang, H.Y., Chen, B., Barter, M., Piersma, T., Zhou, C-F., Li, F-S. and Zhang, Z-W. 2011. Impacts of tidal land reclamation in Bohai Bay, China: ongoing losses of critical Yellow Sea waterbird staging and wintering sites. Bird Conservation International 21: 241-259.

Further web sources of information
Detailed regional assessment and species account from the European Red List of Birds (BirdLife International, 2015)

Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J., Malpas, L. & Symes, A.

Meltofte, H., Morrison, R., Nagy, S., Stroud, D., Wilson, J., Zöckler, C., van Roomen, M. & Balachandran, S.

IUCN Red List evaluators
Symes, A.

Recommended citation
BirdLife International (2015) Species factsheet: Calidris canutus. Downloaded from on 26/11/2015. Recommended citation for factsheets for more than one species: BirdLife International (2015) IUCN Red List for birds. Downloaded from on 26/11/2015.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Red knot (Calidris canutus) 0

Key facts
Current IUCN Red List category Near Threatened
Family Scolopacidae (Sandpipers, Snipes, Phalaropes)
Species name author (Linnaeus, 1758)
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 1,600,000 km2
Country endemic? No
Links to further information
- Additional Information on this species
- Projected distributions under climate change
- 2015 European Red List assessment