Red Knot

The Red Knot is a medium-large, thickset sandpiper with a short, straight bill and relatively short legs, giving it a stocky, compact silhouette quite different from the more delicate build of many other shorebirds.

In breeding plumage, the face, neck, and underparts turn a warm brick-red to salmon color, while the upperparts remain mottled gray, black, and rufous. Nonbreeding birds are much plainer, pale gray above and white below.

Red Knots are famous among ornithologists and conservationists for their extraordinary long-distance migrations, with some populations flying from the southern tip of South America to the high Arctic and back each year.

Key field marks

• Chunky, thickset body with a short, straight bill
• Short legs relative to body size compared to other sandpipers
• Brick-red to salmon face, neck, and underparts in breeding plumage
• Plain gray upperparts, white underparts in nonbreeding plumage
• Often seen in large, dense flocks at key stopover sites

Similar species

• Dunlin: smaller and slimmer with a longer, drooped bill.
• Dowitchers: longer, straighter bills used for a distinctive up-and-down "sewing machine" probing action, different overall shape.
• Ruff (nonbreeding): longer necked and legged, smaller head, less bulky overall.

Habitat

Red Knots use coastal mudflats and sandy beaches, particularly estuaries and bays with abundant invertebrate prey, both during migration stopovers and on the wintering grounds.

Range and migration

They breed on high Arctic tundra in a circumpolar distribution. Some populations, especially the rufa subspecies of the Americas, undertake one of the longest migrations of any bird, traveling from wintering grounds in Tierra del Fuego at the southern tip of South America to Arctic breeding grounds, a round trip of many thousands of miles each year.

Behavior

Red Knots are highly social, gathering in dense, coordinated flocks at key stopover and wintering sites, where they roost and feed together in large numbers.

Voice

Calls include a low, muted "knut" or "whit," from which the species' common name may derive, along with softer contact notes in flocks.

Feeding

During migration, Red Knots famously time their stopover at Delaware Bay in the eastern United States to coincide with the spawning of horseshoe crabs, gorging on the crabs' protein-rich eggs to fuel the final leg of their journey to the Arctic; at other times they feed on small mollusks and crustaceans on mudflats and beaches.

Nesting and breeding

Pairs nest on the ground on open Arctic tundra, laying a clutch of typically four eggs in a shallow, sparsely lined scrape; both parents share incubation, though the female often departs before the young fledge, leaving the male to guard them.