Much has been written recently about the conservation problems of the Red Knot in the Americas, specifically as they relate to the eastern subspecies rufa. The ability to track this population decline has been facilitated by the fact that Red Knots winter in very specific sites and in high densities, so it is but a few places with high numbers. Similarly they concentrate in specific places during migration, notably Delaware Bay in the spring. These concentrations allow for good population estimates, something that would be nearly impossible for more dispersed species such as the Sanderling (Calidris alba). In winter, rufa congregates largely in Bahia Lomas, in Chilean Tierra del Fuego, as well as larger estuaries on the coast of Argentina. Here populations have plummeted from 51 thousand to 17 thousand in just six years. The rufa population is estimated at 18 to 33 thousand now while it was 50 thousand in 1998, and estimated at well over 100 to 150 thousand a decade earlier than that! This species is on a serious decline, and partly this is blamed on decreases in Horshoe Crab egg densities on Delaware Bay due to over harvesting of the crabs. This food source appears to be vital to the northbound migration. In spring the Red Knot is a gorgeous tubby shorebird with reddish underparts, and a complex pattern with reddish bases to the upperpart feathers.