Calidris canutus

Calidris canutus

Red Knot
FWS Focus

Overview

Characteristics
Overview

A robin-sized shorebird, the red knot is truly a master of long-distance aviation. 

Scientific Name

Calidris canutus
Common Name
Red Knot
Kingdom

Location in Taxonomic Tree

Genus

Identification Numbers

TSN:

Characteristics

Characteristic category

Habitat

Characteristics
Habitat

Red knot nesting habitat is in the high Arctic tundra. Migrating and wintering, red knots utilize coastal marine habitats like sandy beaches, estuaries and mudflats for foraging. Red knots can also be found around shorelines of large lakes or freshwater marshes at interior locations in eastern North America. 

Coastal

The land near a shore.

Tundra

A level or rolling treeless plain that is characteristic of arctic and subarctic regions with permanently frozen subsoil.

Lake

A considerable inland body of standing water.

Wetland

Areas such as marshes or swamps that are covered often intermittently with shallow water or have soil saturated with moisture.

Characteristic category

Food

Characteristics
Food

Red knots feed on invertebrates - especially small clams, mussels and snails - but also crustaceans, marine worms, and horseshoe crab (Limulus polyphemus) eggs. 

Large flocks of 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 red knots each year. 

Characteristic category

Behavior

Characteristics
Behavior

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. Red knots winter and migrate in large flocks of hundreds of birds. 

Characteristic category

Physical Characteristics

Characteristics
Size & Shape

Red knot are plump, stocky sandpiper with a straight, medium-sized bill.  

MeasurementsLength: 10 to 11 inches (25-28 cm)Wingspan: 20 inches (50.8 cm)  

Weight

Measurements4.4 to 7.2 oz (125 to 205 grams)

Color & Pattern

Adults in spring are finely mottled with grays, black and light ochre, running into stripes on crown. The throat, breast and sides of red knot’s head are cinnamon-brown. Red knots have a dark gray line through eye. Adults in winter are pale ashy gray above, from crown to rump, with feathers on back narrowly edged with white. The red knot’s underparts white, the breast lightly streaked and speckled, and the flanks narrowly barred with gray.  

Sound

A singing male’s flight songs are a flutelike poorr-mee that becomes a series of poorr-poor.  

Birds flushed from the nest utter a quick whit-whit. Males in conflict give a chatter yodel, written yeh-yeh-yeh, while males courting females produce a high weeee. During most of the year, knots that are foraging or flushed simply give a nasal knutt.

Characteristic category

Lifecycle

Characteristics
Lifecycle

Red knots begin their life cycle as eggs, that are laid in the Arctic tundra. Chicks hatch in about three weeks and fledge after another three weeks. Young feed heavily in preparation for a long migration. Chicks learn to fly around 18 days old, and go on to migrate thousands of miles southward to winter in Florida, Gulf of Mexico, the Caribbean or South America.  

Lifespan

Red knots can live up to 15 years.  

Reproduction

Red knots perform flight and vocal displays during courtship. Knots are monogamous and produce one brood each year. Males arrive at the northern breeding grounds before the females to prepare nesting sites. In June or July, the female lays a clutch, typically with four eggs, that both parents tend. Chicks can leave the nest soon after hatching, and females will leave the breeding grounds before the chicks fledge. 

Geography

Characteristics
Range

Red knots range across shorelines and coasts from Tierra del Fuego, in South America, to Northern Canada. Due to having one of the longest migrations in the animal kingdom, stopover sites are vital to the species survive during long flights.  

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