Calidris tenuirostris (Horsfield, 1821)

Taxonomic Classification

Calidris tenuirostris, commonly known as the great knot, is classified in the genus Calidris and the family Scolopacidae, and is one of the largest species in that genus. While the ruff, C. pugnax, can have larger males due to its pronounced size-related sexual dimorphism, female ruffs are much smaller than great knots. The great knot's sister species, the surfbird C. virgata and the red knot C. canutus, are the next largest after the great knot in the genus.

Size Measurements

Adult great knots measure 26 to 30 cm (10 to 12 in) in length, have a 56 to 66 cm (22 to 26 in) wingspan, and weigh between 115 and 261 g (4.1 to 9.2 oz).

Limb and Bill Morphology

The species has short dark legs and a medium-length, thin, dark bill.

Breeding Plumage Upperparts

Breeding adult great knots have mottled greyish upperparts, with a distinct band of rufous feathers on the scapulars.

Breeding Plumage Underparts

Their face, throat, and breast are heavily spotted with black, and there are additional streaks on the rear belly.

Non-breeding Plumage

In winter, the upperparts of their plumage turn uniformly pale grey.

Breeding Plumage Identification vs Red Knot

The great knot can be distinguished from the red knot by its breeding plumage: breeding red knots have a distinctive red face, throat, and breast.

Non-breeding Plumage Identification

In other plumage stages, the great knot is identifiable by its larger size, longer bill, deeper chest, and more streaked upperparts.

Breeding Habitat

The great knot's breeding habitat is tundra in northeast Siberia, Russia.

Nesting Behavior

It nests on the ground, laying around four eggs in a ground scrape.

Migratory Pattern

The species is strongly migratory, and winters on coasts from southern Asia through to Australia.

Winter Flocking Behavior

In winter, great knots form enormous flocks.

North American Occurrence

Low numbers of the species are recorded most summers in western Alaska, United States, and small numbers winter as far west as Pakistan, Oman, and the United Arab Emirates.

Vagrant Records

It has occurred as a vagrant in Great Britain, Morocco, New Zealand, British Columbia (Canada), and three of the lower 48 states of the United States: Oregon, West Virginia, and Maine.