Global Short Term Trend: Relatively stable to decline of 30%
Global Long Term Trend: Relatively stable to decline of 50%
Comments: Population trend estimates at Delaware Bay and eastern Canadian migration stopover sites for subspecies rufa have been consistently negative over the past several decades, though some of the decline data were not statistically significant (Howe et al. 1989, Clark et al. 1993, Morrison et al. 1994, Morrison, Aubry et al. 2001).
Recent population surveys showed a dramatic decline of the population that winters primarily in South America (main wintering areas on the coasts of Patagonia and Tierra del Fuego, Argentina and Chile, corresponding with subspecies rufa, which comprises a portion of the North American nesting population) (González et al. 2004, Morrison et al. 2004). Totals in 2003 were about 30,000 compared to 67,500 in the mid-1980s. Numbers at the principal wintering site, Bahia Lomas, fell by approximately 50%, from 45,300 in 2000 to 22,000-25,000 in 2002-2003. Numbers at peripheral sites on the coast of Patagonia declined dramatically, decreasing 98% compared to numbers in the mid-1980s. The declines at core sites did not result from a shift of birds within the known wintering (or other) areas, but reflected a general population decline, with most birds now restricted to key sites in Tierra del Fuego (Morrison et al. 2004). These data do not include red knot populations that nest: (1) in the northeastern Canadian arctic (i.e., Queen Elizabeth Islands, Ellesmere Island) or Greenland, which winter in the Old World (C. c. islandica), (2) in northwestern Alaska and Wrangel Island (subspecies roselaari; winter range poorly documented, may include the Pacific coasts of North, Central, and South America, the northern tropical Atlantic coast of South America, the Texas coast, and Florida), or (3) in the Palearctic.
Subspecies roselaari breeds in Alaska and is presumed to include those knots that winter on the Pacific coast of the U.S. and Mexico (Niles et al. 2007). Two other red knot wintering populations of uncertain subspecific status exist in the Western Hemisphere: one in the southeastern United States (about 7,000 birds) and one on the north coast of Brazil (about 7,500 birds); these populations apparently have not suffered the same catastrophic decline as has occurred in the rufa population that winters in Tierra del Fuego (Niles et al. 2007).
Calidris c. islandica populations increased from the late 1970s until 2000; steep decrease since 2000 (Delany and Scott 2002).
Use of Massachusetts Bay as a migration stop evidently has declined from the historical situation (Harrington 2001).