U.S. Fish & Wildlife Service

Northeast RegionConserving the Nature of America

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Credit: Gregory Breese/USFWS
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Credit: Gregory Breese/USFWS
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Credit: Gregory Breese/USFWS
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Credit: Gregory Breese/USFWS
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Rufa Red Knot (Calidris canutus rufa)

 

A robin-sized shorebird, the rufa red knot is truly a master of long-distance aviation. On wingspans of 20 inches, some knots fly more than 9,300 miles from south to north every spring and repeat the trip in reverse every autumn, making this bird one of the longest-distance migrants in the animal kingdom. The knot's unique and impressive life history depends on suitable habitat, food and weather conditions throughout a network of far-flung sites across the Western Hemisphere, from the extreme south of Tierra del Fuego to the far north of the central Canadian Arctic.

 

The rufa red knot spends most of the year in flocks, sometimes with other species. As the knot heads north to breed in the tundra of the central Canadian Arctic, its plumage becomes rusty red. The birds return to gray as they head south to wintering grounds at the southern tip of South America (Tierra del Fuego), in northern Brazil, throughout the Caribbean, and along the southeastern and Gulf coasts of the U.S. into Mexico. Rufa red knots feed on invertebrates, especially small clams, mussels, and snails, but also crustaceans, marine worms, and horseshoe crab (Limulus polyphemus) eggs. On the breeding grounds knots mainly eat insects.

Migrating knots can complete non-stop flights of 1,500 miles or more, converging on vital stopover areas to rest and refuel. Birds arrive at stopover areas with depleted energy reserves and must quickly rebuild their body fat to complete their annual migrations. For example, during their brief 10 to 14-day spring stay in the mid-Atlantic, rufa red knots can nearly double their body weight.

 

Large flocks of rufa red knots arrive at stopover areas along the Delaware Bay and the U.S. Atlantic coast each spring, with many of the birds flying directly from northern Brazil. Spring migration is timed to coincide with the spawning season for the horseshoe crab, whose eggs provide a rich, easily digestible food source. Because it provides abundant horseshoe crab eggs, Delaware Bay is the single most important spring stopover habitat, supporting an estimated 50 to 80 percent of all migrating rufa red knots each year. Mussel beds and small clams on the Atlantic coast are also important food sources for migrating knots, in both spring and fall. Besides Delaware Bay, some key U.S. stopover habitats include the coastal islands of Massachusetts, Virginia, South Carolina, and Georgia. Some rufa red knots that winter on the Gulf coast take an overland migration route, stopping along the rivers of the Mississippi drainage and at saline lakes in the northern U.S. and southern Canadian plains.

 

Red knots in trouble

 

Rufa red knot populations in the U.S. were decimated in the 1800s by commercial hunting for sport and food. Knot hunting in the U.S. ended with passage of the Migratory Bird Treaty Act in 1918, and historical writings show the birds largely recovered. But in the 20th century, coastal development and overharvest of the horseshoe crab took a toll. Rufa red knot numbers in Tierra del Fuego (winter) and Delaware Bay (spring) declined about 75 percent from the 1980s to the 2000s. The smaller populations that remain now face many hurdles to recovery, including sea level rise; coastal development; shoreline stabilization; dredging; reduced food availability at stopover areas; disturbance by vehicles, people, dogs, aircraft, and boats; and climate change.

 

Road to recovery

 

The horseshoe crab harvest is now managed specifically for the protection of the rufa red knot. Knot populations appear to have stabilized in recent years, though at low levels. Listing of the rufa red knot in 2015 brought new protections. Some threats, like climate change, cannot be directly addressed under the ESA. But by limiting other threats – like horseshoe crab overharvest and human disturbance – the Service and our partners are giving the rufa red knot its best shot to adapt and cope with a changing world.

 

Learn more about our approach to recovery:

Recovery Outline

Atlantic Flyway Shorebird Initiative

Guidance and Best Practices for Evaluating and Managing Human Disturbances to Migrating Shorebirds on Coastal Lands in the Northeastern United States

Atlantic States Marine Fisheries Commission Horseshoe Crab Management

U.S. Fish and Wildlife Service Red Knot Research Priorities 2019-2021

More information

Red Knot Fact Sheet

Migration Infographic

Species Profile

Species Status Assessment - NEW

Supplemental Listing Document

Delaware Bay Shorebird Fact Sheet

Horseshoe Crab Fact Sheet

 

Rufa Red Knot Resources

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Help rufa red knots!

  • Respect areas fenced for wildlife. Enjoy watching shorebirds from a distance of at least 400 feet.
  • Obey signs restricting dogs and vehicles on beaches.
  • If dogs are allowed, keep them leashed especially when shorebird flocks are present.
  • When walking on the beach, give shorebird flocks plenty of elbow room – about the length of a football field. Do not allow kids or dogs to chase the birds. Allow even more room when driving.
  • Obey signs restricting motorized boats in remote coastal areas. If boats are allowed, try to keep at least 500 feet away from bird flocks along the shoreline, and avoid creating wakes at natural inlets.
  • Do not feed gulls or other wildlife. Don’t leave or bury trash or food scraps on the beach.
  • Keep cats indoors.
  • Report red knot observations.
  • Report red knots with colored leg flags.
  • Volunteer

Red Knot Facts

red knot fact sheet
Click to view the full size image

red knot infographic
Click to view the full size image

Key Documents

Species Status Assessment - NEW

Supplemental Listing Document

Recovery Outline

Atlantic Flyway Shorebird Initiative

 

 

Last updated: November 24, 2020
    U.S. Fish & Wildlife Service
    Northeast Region
    300 Westgate Center Dr.
    Hadley, MA 01035
    (413) 253-8200
U.S. Fish & Wildlife Service
U.S. Fish & Wildlife Service
Northeast Region


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