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Red Knot rufa subspecies

Red Knot <i>rufa</i> subspecies
   Photo: © Mark Peck

Features: The Red Knot (Calidris canutus rufa) is a robin-sized shorebird with distinctive reddish plumage on its face, neck, and breast during breeding season, which easily distinguishes it from other shorebirds. Feathers on the upper parts of the body have dark brown centres with grayish edges, giving the bird a speckled appearance that effectively camouflages it on its nest in the scrubby vegetation of the Canadian Arctic. Narrow white wingbars help to distinguish it in flight. During the winter, Red Knot plumage is quite plain, with white underparts and a grayish back.

The majority of Red knots overwinter in Tierra del Fuego, Argentina and undertake an amazing 15,000-kilometre migration to the Canadian Arctic each spring for a short breeding season, before heading south again in the fall. During migration, they stop at several staging sites to rest and re-fuel before continuing their journey. Knots use different habitats and food sources on breeding, wintering and staging grounds. On their wintering and migration stopover sites, they inhabit intertidal areas, salt marshes, and brackish lagoons, wherever they can find mollusks and other invertebrates that form the main part of their diet. On their breeding grounds in the Arctic, they depend on insect larvae and other invertebrates for the bulk of their diet.

Status: Endangered Nationally

Range: There are three subspecies of Red Knot in Canada, (rufa, roselaari, and islandica) however, only rufa is thought to occur in Ontario as a transient visitor at staging sites during seasonal migrations. In late May to early June, and again during July and August, large flocks C. c. rufa can be seen in the coastal areas of southwestern Hudson Bay and the west and southern coasts of James Bay. Small concentrations of knots have been observed occasionally at Presqu’ile Provincial Park and Point Pelee, but this is likely as a result of weather conditions that affect migration.

Threats: The rufa subspecies of Red Knot has shown a 70% decline in numbers in the past 15 years. This decline is due in large part to inadequate food supply at the birds’ most important staging site during migration, Delaware Bay, U.S. Spawning horseshoe crabs deposit billions of eggs on the beaches of Delaware Bay, and the knots depend on these eggs to gain weight in order to fly the last 3000 kms to their breeding grounds. Over-harvesting, combined with beach erosion and shoreline development, has decimated the crab population and drastically reduced the availability of eggs. Potential pollution from oil spills in both Delaware Bay and wintering areas, as well as possible toxic algae blooms (otherwise known as red tide) in Uruguay, are additional threats.

Protection: Red Knots are protected under the federal Migratory Birds Convention Act. Strict regulations governing the harvesting of horseshoe crabs have been put into effect in some northeastern, U.S. states to try and stabilize the horseshoe crab population. However, no regulatory mechanisms related to habitat destruction and modification in either Delaware Bay or Tierra del Fuego have been instituted.

Text Sources: COSEWIC 2007

Last Modified Date: June 2010

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