Red Knot (Ivvavik National Park) · iNaturalist Canada

Red Knot

Calidris canutus

Vagrant to Ivvavik ⁴

This species is considered a vagrant to Ivvavik National Park, meaning that it is very rarely seen. It is also an important bird to track because of its declining population (see 'Threats' below). If you see this species and manage to take a photo, please upload it to iNaturalist and/or send it to us directly at yukoncdc@gov.yk.ca. You will be helping us expand the scientific knowledge of this threatened bird.

Description ⁵

The red knot has a more conspicuous plumage during the breeding season than in the winter months. The bill is long, thick, straight and black, and the legs are black or dull green. Throughout the winter, the upperparts are pale grey with blackish primaries and a white stripe across the wing. The head is grey, with white areas above the eye and on the throat. The breast and tail are pale grey, but the flanks, belly and undertail feathers are white. However, during the breeding season the head becomes reddish with brownish mottling on the forehead, crown and back of the neck. The underparts also become red, and the tail develops a dark grey-brown stripe. Juveniles are varying shades of grey with dark edgings on the feathers, a white stripe across the wings and dark grey primaries (2) (5). Following migration the usually plump body is considerably leaner (6).

Biology ⁶

The red knot is a long-distance migrant, covering between 5,000 and 15,000 kilometres, and stopping at least once along the way to feed and build up body fat and protein stores. It probes amongst the sand of estuaries and on shorelines for intertidal invertebrates, mainly small molluscs, but feeds also on crustaceans, horseshoe crab eggs and insects (2). Molluscs are ingested whole and cracked with their muscular gizzard. The size of its gizzard varies flexibly throughout the year, as a consequence of energetic demands and food quality (8). Red knots have unique sensory organs in their bill tips enabling them to detect buried prey without touching them, via water pressure differences in the sediment (comparable to the echolocation of bats) (9). Knots often form mixed species flocks with other shorebird species such as godwits (Limosa species), dunlins (Calidris alpina) and dowitchers (Limnodromus species) (5). Breeding in the tundra of the Arctic Circle, the red knot constructs a nest in a dip between lichen-covered rocks and lays three to four buff-coloured eggs spotted with brown. Both sexes incubate the eggs for 21 to 22 days, but the female departs immediately after hatching. The male takes care of the chicks up to fledging, which takes 18 to 20 days, and then leaves the tundra before the young, to head south to the wintering grounds. At the tundra, knots eat insects, beetles, spiders, small crustaceans, snails and worms (2).

Threats ⁷

The red knot was once the most numerous shorebird in North America, but during the 1800s and early 1900s, it was put under severe hunting pressure on its migration routes (5), becoming far less common. However, the decline has continued despite a massive drop in hunting. Numbers fell in New Jersey from 90,000 in 1989 to 36,000 in 2001, and other counts suggest declines of at least 30 percent in the last 12 years. Whilst this decline in North America is not fully understood, it is thought to be related to the decline in horseshoe crabs, the eggs of which are consumed by migrating red knots (10) (11). Other subspecies also show a serious decline in numbers. As with the American subspecies, this is often thought to be related to declines in prey species, numbers and quality in the wintering and/or stopover areas. For example, it has been shown that shellfisheries in the Wadden Sea negatively affected the survival of red knots (12).

Sources and Credits

More Info

Range Map

iNaturalist.ca Map

Bird	waders
Animal	Bird
Color	brown, grey

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Red Knot

Vagrant to Ivvavik 4

Description 5

Biology 6

Threats 7