The Red Knot is a long-distant migrant shorebird. They breed in the tundra of northern Canada, Europe, and Russia. After breeding, most Red Knots migrate to wintering grounds on the coasts of Africa, South America, and Australia.
Due to their epic migration, Red Knots feed on a wide variety of foods depending on the time of year and their location. On their tundra breeding grounds, they feed on insects and larvae, while small mollusks are a common food at other times of year. Red Knots in the Americas famously depend on the spawning of horseshoe crabs across parts of eastern North America (especially Delaware Bay) during their northward migration. The birds fuel up on the eggs; the Red Knot's threatened status is tied to excessive crab harvesting by humans.
From IUCN Red List: The Red Knot is listed as Near Threatened
on the IUCN Red List and was last assessed in 2015 by BirdLife International. This species has been uplisted to Near Threatened as it almost meets the requirements for listing as threatened under criteria A2abc+3bc+4abc. It has an extremely large range and six subpopulations across which trends are variable. The population trend of the largest subpopulation, islandica, is unclear as is the trend of roselaari. The rufa and canutus subpopulations have both experienced population declines. Two subpopulations use the East Asian-Australasian Flyway and have experienced significant declines owing to loss of habitat in the Yellow Sea. Should new research resolve uncertainties in the trends of several of these subpopulations the species may warrant uplisting or downlisting.