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COSEWIC Assessment and Status Report on the Red Knot in Canada

Habitat

Habitat Requirements

Red Knots use different habitats for breeding and wintering/migration. In the Arctic, knots nest on barren habitats (often less than 5% vegetation) such as windswept ridges, slopes or plateaus. Nest sites are usually in dry, south-facing locations, and may be located near wetlands or lake edges, where the young are led after hatching. Densities are usually low, with nests often 0.75-1 km apart. An analysis of potential breeding habitat characteristics of rufa developed from locations of 21 nests on Southampton Island and relocations of radio-tagged birds over a wider section of the central Arctic (see Figure 6) indicated knots were generally found at elevations of less than 150 m above sea level, less than 50 m from the coast, and in areas with less than 5% vegetation. Foraging habitats can be considerable distances (up to 10 km) from the nest, and are usually in damp or barren areas.

On migration and wintering areas, knots tend to favour coastal areas with extensive intertidal flats, usually sandflats (sometimes mudflats), where the birds feed on bivalves and other benthic invertebrates. On the wintering grounds, major habitats are the massive intertidal sandflats and mudflats at Bahia Lomas, Chile (also Bahia San Sebastian, Argentina) in Tierra del Fuego. At Rio Grande on the Atlantic coast of Tierra del Fuego, Argentina, and on migration areas on the coast of Patagonia, knots also forage on restinga habitats consisting of rocky intertidal platforms that support a variety of invertebrates. During spring migration in Delaware Bay, knots forage on sandy beaches used by nesting horseshoe crabs (Limulus polyphemus), feeding on the eggs of the crabs. They may on occasion also forage on tide wrack on beaches. In addition to sandy beaches, knots use peat banks (mussel spat), salt marshes, brackish lagoons, mangrove areas, and mudflats on migration (and in winter) in southeast USA and in Brazil (Niles et al. 2005).

An important aspect of habitat quality for knots is the proximity of suitable roosting areas that provide an undisturbed area safe from ground or aerial predators.  


Habitat Trends

It is unlikely that any major changes in the extent of breeding habitat have occurred in the Arctic, though long-term changes resulting from climate change are likely to affect knots, probably in a negative fashion (Meltofte et al. 2005). Knot habitats used on migration are thought to have decreased considerably on both the east and west coasts of North America (see Trends section for a fuller discussion). Habitats in South American locations are generally less disturbed, though they face a variety of potential environmental concerns and threats (see Threats section).


Habitat Protection/Ownership

Some of the more important Red Knot habitats have been recognized by various conservation and habitat protection programs and initiatives, providing a variable amount of formal and informal protection (Table 2). These programs include: (1) the Western Hemisphere Shorebird Reserve Network, a non-government organization that identifies and seeks protection for important shorebird sites; (2) the Ramsar Convention, a worldwide intergovernmental treaty that provides the framework for national action and international cooperation for the conservation and wise use of wetlands; (3) the Important Bird Areas (IBA) program of BirdLife International, which identifies and promotes conservation of important areas for birds; and (4) various other designations, often at a national, state, or regional level. These initiatives raise the profile of important areas, and may provide some level of legal protection for key habitats.

Table 2: Recognition/Status of Key Sites Used by Red Knots by Conservation Organizations, Including the Western Hemisphere Shorebird Reserve Network (WHSRN), the Ramsar Convention (Ramsar), the Important Bird Areas Initiative of BirdLife International (IBA), and Other Designations
SiteWHSRNRamsarIBAOther1
Bahia Lomas, Argentina x  
Rio Grande/Bahia San Sebastianxxxx
Peninsula Valdes, Argentina  xx
San Antonio Oeste, Argentinax xx
Lagoa do Peixe, Brazilxx x
Maranhão, Brazilxx  
Delaware Bay, USAxx2 x
James Bay, Canada x3 x
San Francisco Bay, CAx   
Grays Harbor, WAx   
Fraser River estuary, BCx   
Guerrero Negro, Mexico   x
Bahia de Santa Maria, Mexicox   

“x” indicates the site has been officially recognized by the organization.

1 e.g., State or Provincial reserves, wildlife reserves; 2 Delaware estuary; 3 Southern James Bay.