Red Knot

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Red Knot

winter plumage

Conservation status

Least Concern

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Charadriiformes
Family:	Scolopacidae
Genus:	Calidris
Species:	C. canutus

Binomial name

Calidris canutus
Linnaeus, 1758

Distribution and migration routes of the six subspecies of the Red Knot

The Red Knot, Calidris canutus (just Knot in Europe), is a medium sized shorebird which breeds in tundra in the far north of Canada, Europe and Russia.

There are six subspecies, in order of size;

C. c. roselaari (largest)
C. c. rufa
C. c. canutus
C. c. islandica
C. c. rogersi
C. c. piersmai (smallest)

North American birds winter in coastal areas on the Atlantic and Pacific coasts as far south as Argentina as well as to the British Isles. Old World birds migrate to Africa, Papua New Guinea, Australia and New Zealand (see distribution map). This species forms enormous flocks in winter.

The Red Knot nests on the ground, near water, and usually inland. The female lays 3 to 4 eggs in a shallow scrape lined with leaves and moss. Both parents incubate the eggs, but the female leaves before the young fledge. After the young have fledged the male begins his migration south and the young make their first migration on their own.

An adult Red Knot is 23-26 cm long with a 47-53 cm wingspan. It has short dark legs and a medium thin dark bill. The body is mottled grey on top with a cinnamon face, throat and breast and light-coloured rear belly. In winter the plumage becomes uniformly pale grey. canutus, islandica and piersmai are the “darker” subspecies. rogersi has a lighter belly than either roselaari or piersmai, and rufa is the lightest in overall plumage.

The weight varies with subspecies, but is between 100 and 200 g. Red Knots can double their weight prior to migration.

On the breeding grounds, Knots eat mostly spiders and arthropods obtained by surface pecking, and on the wintering grounds they eat a variety of hard-shelled prey such as bivalves, gastropods and small crabs that are ingested whole and crushed by a muscular stomach.

Near the end of the 19th century, large numbers of Knot were shot for food during migration in North America. This bird's numbers have declined in that continent in more recent times due to extensive harvesting of Horseshoe crabs in Delaware Bay, a critical stopover point during spring migration; the birds refuel by eating the eggs laid by these crabs.

It is sometimes said that the Red Knot gets its name from King Cnut, but there is no factual basis for this story. A more likely etymology is that the name is onomatopoeic, based on the bird's grunting call note.

C.c.canutus and C.c.islandica are among the subspecies to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

[edit] References

BirdLife International (2004). Calidris canutus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006. Database entry includes justification for why this species is of least concern
Shorebirds by Hayman, Marchant and Prater ISBN 0-395-60237-8
Piersma, T., de Goeij, T. P. & Tulp, I. 1993 An evaluation of intertidal feeding habitats from a shorebird perspective: towards relevant comparisons between temperate and tropical mudflats. Netherlands Journal of Sea Research 31, 503-512.
Piersma, T., Dietz, M. W., Dekinga, A., Nebel, S., van Gils, J. A., Battley, P. F. & Spaans, B. 1999 Reversible size-changes in stomachs of shorebirds: when, to what extent, and why? Acta Ornithologia 34, 175-181.
Tomkovich, P. S. 1992 An analysis of the geographic variability in knots Calidris canutus based on museum skins. Wader Study Group Bulletin 64 Supplement, 17-23.
Tomkovich, P. S. 2001 A new subspecies of Red Knot Calidris canutus from the New Siberian Islands. Bulletin of the British Ornithologists Club 121, 257-263.
Tulp, I., Schekkerman, H., Piersma, T., Jukema, J., de Goeij, P. & van de Kam, J. 1998 Breeding waders at Cape Sterlegova, northern Taimyr, in 1994. Zeist: WIWO - Report 61.