The red knot
Of the six Calidris canutus subspecies, rufa travels the longest distance, between breeding areas in the Canadian Artic and wintering areas in Patagonia and Tierra del Fuego.
Although the causes of the population crash are not yet fully understood, the dramatic decline is mainly attributed to the low availability of horseshoe crab eggs in Delaware Bay, USA, a key stopover site for Red Knot Calidris canutus rufa. The lack of eggs has been attributed to an elevated harvest of adult crabs for bait in the conch and eel fishing industries. Studies show that Red Knot individuals with lower body weight at departure in Delaware Bay have lower survival than heavier birds.
http://www.sciencedaily.com/releases...0816162204.htm
Amazing travel - Patagonia to the arctic , depends on feeding heavily on horseshoe crab eggs on Delaware Bay.
Excellent Nature show btw
http://wwd.wgbh.org/tv/program/natur...le-two-species