Many migrant shorebirds make a round trip of over 19,000 miles! This impressive journey is accomplished in a series of flights that stop at strategic sites to refuel. The eggs of the American Horseshoe crab are a critical food source for 11 species of migrating shorebirds. A decline in egg production due to overharvesting or pollution would devastate the migrant shorebird population.
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Case Study: The Delaware Estuary
Delaware Bay is the world's largest spawning ground for horseshoe crabs, and so it is no surprise that the Delaware Estuary is one of the largest staging areas for shorebirds in North America. It is estimated that 425,000 to 1,000,000 migratory shorebirds visit the Delaware Bay to refuel their energy reserves before setting out to continue their northbound migration. The eggs are usually pilfered from nests that were disrupted by waves. Thus, the feeding frenzy of the shorebirds does not have negatively affect the breeding success of the horseshoe crabs.
References:
Botton, Mark and Harrington, Brian. The American Horseshoe Crab: Synchronies in Migration: Shorebirds, Horseshoe Crabs, and Delaware Bay. Cambridge, MA: Harvard University Press, 2004.
Ecological Research & Development Group (ERDG): The Horseshoe Crab. c2002-2009. Dover, DE. http://horseshoecrab.org/
Ecological Research & Development Group (ERDG): The Horseshoe Crab. c2002-2009. Dover, DE. http://horseshoecrab.org/