New Jersey Field Office
Northeast Region

Rufa Red Knot (Calidris canutus rufa) [threatened]

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Additional Information

Red knot


In the U.S., Atlantic and bay beaches and mudflats

Clams, mussels, snails, horseshoe crab eggs, other invertebrates

Main Threats:
Shoreline development
Reduced food availability
Climate change

Fun Fact:
The red knot makes one of the longest distance migrations known in the animal kingdom.


Map of red knot distribution in the US
Red knot range in the U.S.


Map of red knot distribution in New Jersey by municipality
Red knot distribution in New Jersey (municipal boundaries)

The red knot was added to the list of Federal candidate species in 2006. A final rule to list the rufa subspecies as threatened under the Endangered Species Act was published on December 11, 2014, with an effective date of January 12, 2015. Red knots are federally protected under the Migratory Bird Treaty Act, and are State-listed as endangered.

At 9 to 10 inches long, the red knot is a large, bulky sandpiper with a short, straight, black bill. During the breeding season, the legs are dark brown to black, and the breast and belly are a characteristic russet color that ranges from salmon-red to brick-red. Males are generally brighter shades of red, with a more distinct line through the eye. When not breeding, both sexes look alike—plain gray above and dirty white below with faint, dark streaking. As with most shorebirds, the long-winged, strong-flying knots fly in groups, sometimes with other species. Red knots feed on invertebrates, especially small clams, mussels, and snails, but also crustaceans, marine worms, and horseshoe crab eggs. On the breeding grounds knots mainly eat insects.

Small numbers of red knots may occur in New Jersey year-round, while large numbers of birds rely on New Jersey's coastal stopover habitats during the spring (mid-May through early June) and fall (late-July through November) migration periods. Smaller numbers of knots may spend all or part of the winter in New Jersey.

The primary wintering areas for the rufa red knot include the southern tip of South America, northern Brazil, the Caribbean, and the southeastern and Gulf coasts of the U.S. The rufa red knot breeds in the tundra of the central Canadian Arctic. Some of these robin-sized shorebirds fly more than 9,300 miles from south to north every spring and reverse the trip every autumn, making the rufa red knot one of the longest-distance migrating animals. Migrating red knots can complete non-stop flights of 1,500 miles or more, converging on vital stopover areas to rest and refuel along the way. Large flocks of red knots arrive at stopover areas along the Delaware Bay and New Jersey's Atlantic coast each spring, with many of the birds having flown directly from northern Brazil. The spring migration is timed to coincide with the spawning season for the horseshoe crab (Limulus polyphemus). Horseshoe crab eggs provide a rich, easily digestible food source for migrating birds. Mussel beds on New Jersey's southern Atlantic coast are also an important food source for migrating knots. Birds arrive at stopover areas with depleted energy reserves and must quickly rebuild their body fat to complete their migration to Arctic breeding areas. During their brief 10 to 14-day spring stay in the mid-Atlantic, red knots can nearly double their body weight.

Threats to the red knot include 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.


Species Range: Winter: Chile, Argentina, Brazil, Carribbean, U.S. coasts from Texas to North Carolina with smaller numbers north along the Atlantic as far as southern Canada. Breeding: central Canadian Arctic from northern Hudson Bay to the southern Queen Elizabeth Islands. Migration: Atlantic and Gulf coasts of South America, the U.S., and Canada; the Caribbean; interior flyways across South America; interior flyways across the U.S. and Canada west as far as Alberta (Canada), Montanna, Wyoming, Colorado, and Texas.

Distribution in New Jersey: Transient red knots may be found anywhere along New Jersey's coasts in nearly every month, and may move over inland areas during migration. Large numbers of migrating birds are known to use stopover habitats in Cumberland, Cape May, and Atlantic Counties.

Examples of actions that may affect this species

The following is provided as technical assistance only and is not intended as a comprehensive list of all activities that may affect this species.

  • Projects involving modification of beaches, dunes, mudflats, peat banks, sandbars, shoals, or other red knot habitats (e.g., groins, jetties, sea walls, revetments, bulkheads, rip-rap, beach nourishment, nearshore dredging, dredge spoil disposal, sand mining/borrowing, beach bulldozing, sandbagging, sand fencing, vegetation planting/alteration/removal, deliberate or possible introduction of non-native vegetation, beach raking/mechanized grooming, boardwalks, aquaculture development).

  • Construction or project activities likely to disturb red knots (e.g., proposed to take place in/near red knot habitat at times of year that the birds are typically present).

  • Projects, activities or policies likely to indirectly increase access or use of red knot habitats by humans and/or predators at times of year that the birds are typically present (e.g., commercial/residential development, beach access structures, boardwalks, pavilions, bridges/roads/ferries/trails, marinas, posts or other avian predator perches, structures or habitat features likely to encourage predator nesting/denning, trash cans or other predator attractants, feral cat colonies, policy changes likely to increase human use).

  • Projects, activities or policies with potential to impact the red knot’s intertidal invertebrate prey species, primarily blue mussel spat (Mytilus edulis), small clams (e.g.Donax and Mulinia spp.), and horseshoe crab (Limulus polyphemus) eggs (e.g., commercial harvest, aquaculture, deliberate or possible introduction of non-native marine species, sediment placement/disposal, heavy equipment use, intensive vehicle use).

  • Wind turbine development.

  • Response planning for oil or contaminant spills, storms, or harmful algal blooms. (Actual response activities would be handled as emergency consultations.)

Best Management Practices

The following Best Management Practices are examples of typical Conservation Measures frequently recommended by the New Jersey Field Office in the course of consultation or technical assistance.

  • Avoid new coastal developments in and near key red knot habitats.
  • Avoid hard or intensive shoreline stabilization in sparsely developed areas. Preferentially utilize living shorelines techniques. Design projects to incorporate wide, sparsely-vegetated, minimally-stabilized beaches and mudflats. Design projects to preserve natural coastal processes and inlet dynamics.

  • Evaluate development setbacks to allow for habitat migration.
  • Plan beach nourishments to minimize adverse effects to red knots, their prey, and their habitats. Select clean sediment with a close grain size match to the native beach. To the extent practicable, schedule nourishment at times of year that minimize red knot disturbance and depression of the prey base. (See Rice 2009 for other best management practices). Engage local communities in post-nourishment beach management, including maintaining suitable habitat, managing disturbance, and managing predators.

  • Avoid or minimize vegetation planting in red knot habitat. When planting is necessary, use only native, non-woody plant species. Use care to avoid accidental introductions of non-native plants (e.g., clean construction equipment off-site before use).

  • Avoid or minimize beach raking in red knot habitats at those times of year when the birds are typically present.

  • Minimize and monitor disturbance of red knots during construction or project activities.

  • Minimize and monitor disturbance of red knots from other human activities.
  • Minimize and monitor disturbance of red knots from predators.

  • Avoid activities likely to impact horseshoe crabs by potentially entrapping, entangling, or blocking adults; entraining larvae; interfering with spawning; or disturbing spawning habitat.

  • Avoid deliberate introductions of non-native marine species (e.g., avoid aquaculture of nonnative species). Use care to avoid accidental introductions of non-native marine species and marine diseases (e.g., avoid ballast water discharges near red knot habitat).

  • Site both terrestrial and offshore wind turbines away from important red knot habitats and flight paths. Include red knots in pre- and post-construction monitoring plans.

  • Include red knots and their habitats in response plans for oil or contaminant spills, storms, and harmful algal blooms, including provisions for emergency consultation.

What to do if this species occurs on your property or project site

  • Contact the Service early in planning for any project or activity that may affect red knots or their habitat; see New Jersey Field Office Procedures for Consultation and Technical Assistance for instructions. Through the technical assistance or consultation processes of the Endangered Species Act, the Service will provide project-specific recommendations to avoid or minimize adverse effects to listed species.

  • Individual beach-front property owners can also contact the Service for proactive conservation recommendations. Most land in New Jersey is privately owned. Voluntary conservation efforts by New Jersey's residents are critical in the conservation and recovery of threatened and endangered species.

  • Municipalities and other beach managers are encouraged to contact the Service for conservation recommendations to benefit listed species. See Beach Management Planning in New Jersey [PDF].

  • Also see "Endangered Species and You" Frequently Asked Questions.


Last updated: February 19, 2021
New Jersey Field Office
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