Red knot (Calidris canutus) CMS STATUS Appendix I & II CMS INSTRUMENT(S) African-Eurasian Waterbird Agreement (AEWA)
The red knot is a migratory shorebird that travels up to 20,000 km twice a year from its breeding grounds on the high Arctic tundra to its southern non-breeding sites. Along with having one of the longest total migrations of any bird, some populations also fly as much as 8,000–9,000 km between stopover sites in a single flight. As a shellfish-eating specialist avoiding pathogen-rich freshwater habitats, the red knot relies on the few large tidal flats with abundant food resources that the world has to offer. To undertake the physiologically demanding flight from West Africa to northern Siberia, for example, Calidris c. canutus refuels during three weeks of fast feeding in the national parks of Banc d’Arguin in Mauritania and the European Wadden Sea. After nearly doubling its weight, it burns off stored fat during the 3 or more days of non-stop flying.
Threats to migration pathways
Of the six subspecies of red knot, one is now stable, four are in decline, and the trend in the sixth population is unclear. These declines can be attributed to the loss of important feeding areas and food sources along its migration routes. Both C. c. canutus and C. c. islandica, for example, are highly dependent upon the shellfish resources of the Wadden Sea along the East Atlantic flyway. However, as a result of embanking tidal habitats, and mechanical shellfish harvesting in parts of the Wadden Sea, both populations have suffered significant declines.
Similar situations exist for other knot populations. In China and Korea, for example, large-scale reclamation projects have already destroyed over 50 per cent of the tidal flats in the Yellow Sea over the last 30 years with much more underway, putting enormous pressure on both the C. c. piersmai and C. c. rogersi populations that are unique to the East Asian-Australasian Flyway. Along the West Atlantic flyway, overharvesting of horseshoe crabs in Delaware Bay has resulted in a shortage of crab eggs for C. c. rufa and other shorebirds. Their population has plummeted from over 100,000 birds in 2001 to fewer than 20,000 by 2011.