The red knot (Calidris canutus) is a medium-sized shorebird in the sandpiper family, Scolopacidae. It breeds across the high Arctic of Canada, Greenland, Europe and Russia, and undertakes some of the longest migrations of any landbird. Six subspecies are recognised, wintering on coasts from western Africa to Australia, New Zealand and South America. It feeds on arthropods and larvae on its breeding grounds and mainly on molluscs and other marine invertebrates during migration and winter. The red knot is a relatively large sandpiper with short dark legs and a thin dark bill. In winter it is mostly pale grey, while breeding adults develop distinctive reddish-cinnamon underparts; the exact plumage varies between subspecies. Although widespread, some populations have declined because of habitat loss, climate change and reduced food availability. This red knot in breeding plumage was photographed in Delaware Bay in New Jersey, United States.

Photograph credit: Chuck Homler