Calidris

Calidris
Red knot (Calidris canutus) in juvenile plumage, Brittany, France
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Charadriiformes
Family:	Scolopacidae
Genus:	Calidris Merrem, 1804
Type species
Tringa calidris[1] = Tringa canutus Gmelin, 1789
Synonyms
Philomachus Merrem, 1804 Ereunetes Illiger, 1811 Erolia Vieillot, 1816 Limicola Koch, 1816 Machetes Cuvier, 1817 Eurynorhynchus Nilsson, 1821 Crocethia Billberg, 1828 Canutus Brehm, 1831 Aphriza Audubon, 1839 Tryngites Cabanis, 1857 Micropalama Baird, 1858

Calidris is a genus of Arctic-breeding, strongly migratory wading birds in the family Scolopacidae. These birds form huge mixed flocks on coasts and estuaries in winter. They are small to medium-sized sandpipers, long-winged and relatively short-billed; some are difficult to identify because of the similarity between species, and various breeding, non-breeding, juvenile, and moulting plumages. With a few exceptions, they have a fairly stereotypical colour pattern, being brownish above and lighter, usually white or buffy coloured, on much of the underside. They often have a lighter supercilium above brownish cheeks.^[2] The species are variously known in English as sandpipers or (particularly the smaller species) stints; some have their own unique names, with dunlin (a mediaeval name meaning "[small] brown bird"), knot (imitative of its call), ruff (named after its male display plumage), and sanderling and surfbird (named after their habitat and behaviour).^[3] In North America, the smaller species are often known colloquially as peeps.

Their bills are flexible, able to exhibit rhynchokinesis,^[4] and have sensitive tips which contain numerous corpuscles of Herbst. This enables the birds to locate buried prey items, which they typically seek with restless running and probing.^[5] Migratory shorebirds are shown to have declined in reproductive traits because of temporal changes of their breeding seasons.^[6]

Taxonomy

Little Stint at Jamnagar, India

Temminck's stint at Jamnagar, India

Long-toed stint (Calidris subminuta) in Kerala

The genus Calidris was introduced in 1804 by the German naturalist Blasius Merrem with the red knot as the type species.^[7][8] The genus name is from Ancient Greek kalidris or skalidris, a term used by Aristotle for an unidentified grey-coloured waterside bird.^[9]

Many of the species have been treated under other generic names at various times in the past, but these treatments leave Calidris polyphyletic;^[10][11][12] synonyms are in brackets in the list below.

The genus contain 24 species:^[13]

• Red knot Calidris canutus
• Great knot Calidris tenuirostris
• Surfbird Calidris virgata (syn. Aphriza virgata)
• Ruff Calidris pugnax (syn. Philomachus pugnax)
• Sharp-tailed sandpiper Calidris acuminata
• Broad-billed sandpiper Calidris falcinellus (syn. Limicola falcinellus)
• Curlew sandpiper Calidris ferruginea (syn. Erolia ferruginea)
• Stilt sandpiper Calidris himantopus (syn. Micropalama himantopus)
• Spoon-billed sandpiper Calidris pygmaea (syn. Eurynorhynchus pygmaeus)
• Red-necked stint Calidris ruficollis
• Temminck's stint Calidris temminckii
• Long-toed stint Calidris subminuta
• Buff-breasted sandpiper Calidris subruficollis (syn. Tryngites subruficollis)
• Sanderling Calidris alba (syn. Crocethia alba)
• Dunlin Calidris alpina
• Purple sandpiper Calidris maritima
• Rock sandpiper Calidris ptilocnemis
• Baird's sandpiper Calidris bairdii
• Pectoral sandpiper Calidris melanotos
• Semipalmated sandpiper Calidris pusilla (syn. Ereunetes pusillus)
• Western sandpiper Calidris mauri
• Little stint Calidris minuta
• Least sandpiper Calidris minutilla
• White-rumped sandpiper Calidris fuscicollis

The following species-level cladogram is based on a molecular phylogenetic study by David Černý and Rossy Natale that was published in 2022. Some of the nodes are only weakly supported by the sequence data.^[12]

Calidris

Red knot – Calidris canutus Great knot – Calidris tenuirostris Surfbird – Calidris virgata Ruff – Calidris pugnax Sharp-tailed sandpiper – Calidris acuminata Broad-billed sandpiper – Calidris falcinellus Curlew sandpiper – Calidris ferruginea Stilt sandpiper – Calidris himantopus Spoon-billed sandpiper – Calidris pygmaea Red-necked stint – Calidris ruficollis Long-toed stint – Calidris subminuta Temminck's stint – Calidris temminckii Buff-breasted sandpiper – Calidris subruficollis Sanderling – Calidris alba Dunlin – Calidris alpina Purple sandpiper – Calidris maritima Rock sandpiper – Calidris ptilocnemis Baird's sandpiper – Calidris bairdii Little stint – Calidris minuta White-rumped sandpiper – Calidris fuscicollis Least sandpiper – Calidris minutilla Pectoral sandpiper – Calidris melanotos Western sandpiper – Calidris mauri Semipalmated sandpiper – Calidris pusilla

Hybrids

Several hybrids have been discovered between different species in the genus. See Hybridisation in shorebirds for further details.

References

1. "Scolopacidae". aviansystematics.org. The Trust for Avian Systematics. Retrieved 26 July 2023.
2. Hayman, Peter; Marchant, John; Prater, Tony (1986). Shorebirds. London: Croom Helm. pp. 182–209, 363–387. ISBN 0-7099-2034-2.
3. Lockwood, William Burley (1984). The Oxford Book of British Bird Names. Oxford ; New York: Oxford University Press, USA. pp. 55, 92, 132, 133, 147. ISBN 0-19-214155-4.
4. Estrella, Sora M.; Masero, José A. (1 November 2007). "The use of distal rhynchokinesis by birds feeding in water". Journal of Experimental Biology. 210 (21): 3757–3762. doi:10.1242/jeb.007690. ISSN 1477-9145. Retrieved 24 February 2026.
5. Nebel, S.; Jackson, D.L.; Elner, R.W. (2005). "Functional association of bill morphology and foraging behaviour in calidrid sandpipers" (PDF). Animal Biology. 55 (3): 235–243. doi:10.1163/1570756054472818. Archived from the original (PDF) on 10 June 2011. Retrieved 3 June 2016.
6. Weiser, Emily L.; Brown, Stephen C.; Lanctot, Richard B.; Gates, H. River; Abraham, Kenneth F.; Bentzen, Rebecca L.; Bêty, Joël; Boldenow, Megan L.; Brook, Rodney W.; Donnelly, Tyrone F.; English, Willow B.; Flemming, Scott A.; Franks, Samantha E.; Gilchrist, H. Grant; Giroux, Marie-Andrée (February 2018). "Life-history tradeoffs revealed by seasonal declines in reproductive traits of Arctic-breeding shorebirds". Journal of Avian Biology. 49 (2): 1. Bibcode:2018JAvBi..49....1W. doi:10.1111/jav.01531. ISSN 0908-8857.
7. Merrem, Blasius (8 June 1804). "Naturgeschichte". Allgemeine Literatur-Zeitung (in German). 168. Col. 542. Published anonymously.
8. Peters, James Lee, ed. (1934). Check-List of Birds of the World. Vol. 2. Cambridge, Massachusetts: Harvard University Press. p. 280.
9. Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. p. 84. ISBN 978-1-4081-2501-4.
10. Thomas, Gavin H; Wills, Matthew A; Székely, Tamás (24 August 2004). "A supertree approach to shorebird phylogeny". BMC Evolutionary Biology. 4 (1). doi:10.1186/1471-2148-4-28. ISSN 1471-2148. PMC 515296. PMID 15329156.
11. Gibson, Rosemary; Baker, Allan (2012). "Multiple gene sequences resolve phylogenetic relationships in the shorebird suborder Scolopaci (Aves: Charadriiformes)". Molecular Phylogenetics and Evolution. 64 (1): 66–72. doi:10.1016/j.ympev.2012.03.008. Retrieved 12 September 2025.
12. Černý, David; Natale, Rossy (2022). "Comprehensive taxon sampling and vetted fossils help clarify the time tree of shorebirds (Aves, Charadriiformes)" (PDF). Molecular Phylogenetics and Evolution. 177 107620. Bibcode:2022MolPE.17707620C. doi:10.1016/j.ympev.2022.107620. PMID 36038056.
13. AviList Core Team (2025). "AviList: The Global Avian Checklist, v2025". doi:10.2173/avilist.v2025. Retrieved 24 February 2026.