Red Knot

Calidris canutus

A robin-sized shorebird that flies up to about 19,000 miles a year and refuels on horseshoe crab eggs in Delaware Bay.

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About the Red Knot

Red knots are about the size of a robin, 9 to 11 inches long, and weigh 4.5 to 7 ounces, about as much as an apple. In the breeding season they are rusty orange below. One group, the rufa red knot, breeds in the Canadian Arctic and winters as far south as Tierra del Fuego. Red knots swallow mussels and clams whole and crush them in a strong gizzard.^[1]

Quick facts

Scientific name: Calidris canutus^[1]
Size: 9 to 11 inches long; 22.5- to 24-inch wingspan.^[1]
Weight: 4.5 to 7 ounces.^[1]
Lifespan: Up to 15 years.^[1]
Diet: Mussels and clams swallowed whole, plus shrimp, worms, insects and horseshoe crab eggs.^[1]
Habitat: Arctic tundra for nesting; coastlines in migration and winter.^[1]
Where it lives: Breeds in the Arctic; winters from the U.S. coast to southern South America.^[1]
Group life: Pairs when nesting; large flocks in migration and winter.^[1]
Babies: Nests on the ground in open tundra.^[1]
Conservation status: Near Threatened (IUCN Red List, assessed 2024).^[2]

Fun facts

Some red knots fly over 9,000 miles one way.^[1]
A red knot weighs about as much as an apple.^[1]
Red knots eat clams shell and all.^[1]

Vocabulary

migrate: To travel from one region to another with the seasons.
gizzard: A muscular part of a bird's stomach that grinds food.
molluscivore: An animal that eats mostly mollusks.
camouflage: Colors or patterns that help an animal blend in.
near threatened: A conservation label meaning a species may soon be at risk of dying out if things don't improve.

See it in person

Smithsonian's National ZooWashington, D.C. · Bird HouseSee this animal on the zoo's website ↗

These zoos had this animal when we gathered our information, but animals sometimes move. Check the zoo's website or contact the zoo before you visit.

Sources

[1] Smithsonian's National Zoo & Conservation Biology Institute. “Red knot.” https://nationalzoo.si.edu/animals/red-knot (accessed 2026-10-08)
[2] IUCN Red List of Threatened Species. “Calidris canutus (Red Knot).” https://www.iucnredlist.org/species/22693363/154080160 (accessed 2026-10-08)

Facts last checked 2026-10-08.

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