Twice a year, the rufa red knot performs one of the planet's most amazing migrations. After wintering in the southern reaches of Argentina and Chile, the red knot will fly roughly 9,300 miles (15,000 kilometers) north, eventually reaching the Canadian Arctic for a summer of mating and breeding. Come fall, it will return south, this robin-size bird with a mere 20-inch (51-centimeter) wingspan flying without rest for stretches of up to 1,500 miles (2,400 kilometers).
For this incredible voyage, Calidris canutus needs fuel, and a lot of it. As it happens, one of its main food supplies, the eggs of horseshoe crabs in the Delaware Bay, where the birds recharge for the final leg of their journey, has become scarce, and red knot populations are suffering.
The population declines are bad enough that last Friday, the U.S. Fish and Wildlife Service (FWS) officially proposed "threatened" status for the rufa red knot under the Endangered Species Act (ESA).