Delaware Bay — One
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
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
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
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.
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.