Red Knot (Calidris canutus)
The Red Knot (Calidris canutus) has been identified as a focal species due to drastic declines in populations of North American subspecies, especially rufa whose population has declined by more than 75% within the past 20 years. A long-distance migrant that breeds in the Arctic, some knots winter along the coast of the southeastern U.S. while others migrate to the southern tip of South America. Their annual migrations are completed through a series of flights, each of which may cover thousands of kilometers and require abundant food supplies to build up the necessary energy resources to fuel these flights. Delaware Bay is a well-know spring stopover site for migrating Red Knots, where the birds feed on horseshoe crab eggs to rapidly gain weight for the next leg of their journey to their Arctic breeding grounds. This sandpiper is vulnerable during migration due to loss of important food sources, such as the overharvesting of horseshoe crabs in Delaware Bay, and also to disturbance and habitat loss at stopover sites.
Decreased foraging success during migration has been linked to decreased breeding success and the probable increased mortality of adults. Wintering knots tend to concentrate at a few localities where habitat loss or reduced food availability can influence a sizable proportion of entire populations. Additionally, climate change may have long-term effects on its coastal foraging areas due to sea level rise and its Arctic breeding grounds due to habitat change.
Baker AJ, Gonzalez PM, Perisma T, Niles LJ, I de LS do Nascimento LJ, Atkinson PW, Clark NA, Minton CDT, Peck M, Aarts G. 2004. Rapid population decline in Red Knots: Fitness consequences of decreased refuelling rates and late arrival in Delaware Bay. Proceedings of the Royal Society of London, Series B. 271:875-882.
Harrington, BA. 2001. Red Knot (Calidris canutus). In: The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology. Retrieved from http://bna.birds.cornell.edu/bna/species/563/articles/introduction.
February 3, 2012