About Calidris tenuirostris (Horsfield, 1821)
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. 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). The species has short dark legs and a medium-length, thin, dark bill. Breeding adult great knots have mottled greyish upperparts, with a distinct band of rufous feathers on the scapulars. Their face, throat, and breast are heavily spotted with black, and there are additional streaks on the rear belly. In winter, the upperparts of their plumage turn uniformly pale grey. 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. In other plumage stages, the great knot is identifiable by its larger size, longer bill, deeper chest, and more streaked upperparts. The great knot's breeding habitat is tundra in northeast Siberia, Russia. It nests on the ground, laying around four eggs in a ground scrape. The species is strongly migratory, and winters on coasts from southern Asia through to Australia. In winter, great knots form enormous flocks. 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. 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.
