Every spring on the Atlantic Coast, the sky turns scarlet as red knots descend onto local beaches to search for meals as they prepare to fly north. Adorned with a red breast and a dark, russet back during breeding season, red knots travel more than 9,000 miles from South America to the Arctic in one of Earth’s longest migratory events.

This long journey requires immense stamina, which is why these shorebirds will stop to feed along the East Coast of the United States. Their northbound trip along the Atlantic coincides with the spawning of horseshoe crabs, and stopover sites with ample food supplies, such as horseshoe crab eggs, are critical. Unfortunately, horseshoe crab populations are either declining or being maintained at impoverished levels. It’s estimated that Delaware Bay alone supports 50% to 80% of the migrating population of red knots, with the remainder known to stop in South Carolina, among other states.

Defenders' Impact

Defenders works to protect rivers, marshes and coastal habitat from pollution and development. We are pursuing litigation against the US Fish and Wildlife Service to prevent the harvest of horseshoe crabs in Cape Romain National Wildlife Refuge and are advocating for the adoption of a synthetic alternative to horseshoe crab blood.

Red knots are protected under the Migratory Bird Treaty Act (MBTA), which prevents the unlawful killing or take of birds during their migration. Defenders is in court challenging the reinterpretation of the MBTA by the Trump administration and we are working with other organizations to overturn the decision. 


Red knots are threatened by overharvesting of horseshoe crabs, climate change, coastal development and other disturbances.

Protection Status
Endangered Species Act
IUCN Red List
 Near Threatened
 Not Listed
What You Can Do

Overturn flipped horseshoe crabs on beaches, give space to feeding flocks and remove human debris from beaches. 

Latin Name
Calidris canutus rufa
9-10 in. long and 19-21 in. wingspan
Roughly 13 years, but the oldest on record was at least 20 years old

Red knots migrate through on sandy beaches and mudflats along the North American coast during spring and fall while they fly between wintering grounds in South America, among other places, and summer breeding grounds in the Arctic tundra. 




Red knots gather to migrate and roost in dense flocks. When foraging for food, red knots probe into the sand and mud with their bills and find food by touch. 


Red knots nest on the ground in the tundra, usually near water. The female lays 3-4 eggs which hatch in  21-22 days. 


Red knots mainly feed on mollusks, insects, horseshoe crab and fish eggs, and may eat some plant material early in the season before finding invertebrates. 


Spring migration of red knots, Delaware Bay
Beaufort, N.C.

Fisheries Commission Rejects Female Horseshoe Crab Harvest Proposal for Delaware Bay

Conservation groups commended today’s decision by the Atlantic States Marine Fisheries Commission to forego a 2024 bait harvest of female horseshoe crabs in Delaware Bay

Wildlife and Wild Places

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