Migratory Shorebirds

Delaware Bay — One Link
in a 10,000-Mile-Long Chain

During May and early June, the shores of Delaware Bay resonate with the cheerful chattering of more than 20 species of migratory shorebirds. Delaware Bay provides an ecologically important stepping-stone for the birds' spring pilgrimage to Arctic nesting grounds.The Delaware Bay is the largest spring staging area for shorebirds in eastern North America. A staging site is an area with plentiful food where migrating birds gather to replenish themselves before continuing on their journey. Staging sites serve as a link in a chain connecting wintering areas with breeding grounds, sites for which there are no alternatives.

Place cursor on map to see the Southward Migration

World Travelers

Shorebirds begin to arrive in early May. The numbers of birds soar upward during mid-month and usually peak between May 18 and 24 (in some years as late as May 28). They have traveled from the coasts of Brazil, Patagonia, and Tierra del Fuego, from desert beaches of Chile and Peru, and from mud flats in Suriname, Venezuela, and the Guyanas. After several days of non-stop flight, and having come as far as 10,000 miles, they reach the bay beaches depleted of their energy reserves. Luckily, nature provides an abundant food supply in this area at just this time of year: the eggs of hundreds of thousands of horseshoe crabs that have migrated to Delaware Bay beaches to spawn.

A Feast for Feathered Friends

The shorebirds spend between two to three weeks gorging primarily on fresh horseshoe crab eggs, although worms and small bivalves are also plentiful. High in protein and fat, the eggs are an energy-rich source of food. This high-calorie diet enables the birds to nearly double or triple their body weight before continuing on to Arctic nesting areas.

More Than a Million Mouths to Feed

Each spring, scientists from the Delaware and New Jersey Divisions of Fish and Wildlife conduct weekly aerial surveys of migratory shorebirds on Delaware Bay beaches. In May 2001, scientists observed more than 775,000 shorebirds along beach habitat. Ninety-five percent of these birds were represented by four species: red knots, ruddy turnstones, semipalmated sandpipers, and dunlins. Migratory shorebirds are also known to utilize marshes and back-bay habitats. Thus, throughout their spring migration, the actual number of shorebirds using Delaware Bay as a staging ground may surpass one million. Click here to meet a few of these Delaware diners.

The recent decline in the horseshoe crab population appears to correlate with a decline in migrating shorebird populations. Click here to learn more about the problems facing migratory shorebirds.

Click here to learn why horseshoe crabs are decreasing in abundance.