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Horseshoe Crabs and Migrating Shorebirds Return to the Delaware Bay
Spring Arrival

It's mid-spring, the time of year when horseshoe crabs emerge from the depths of the ocean to lay their eggs on the beaches of the Delaware Bay. Horseshoe crabs are ancient creatures, over 300 million years old, older than the dinosaurs. Each year, Delaware Bay beaches host more breeding horsehoe crabs than anywhere else in the world.

Also landing on the beaches of the Delaware Bay are hundreds of thousands of migrating shorebirds, who timed their arrival to that of the crabs. The birds are tired and starving, having flown for thousands of miles from South and Central America where they spent the winter. Their stop at the bay is only temporary, two weeks of rest and refueling on the eggs laid by the horseshoe crabs. The fat-rich eggs help the birds regain bulk and provide the energy needed for the last leg of their journey, a non-stop, two thousand miles to their Arctic breeding grounds.

Horseshoe crabs and shorebirds are ecologically linked. The crab's eggs are crucial to the birds' survival; depleted of fat reserves on arrival, many will double, sometimes triple their body weight during their Delaware Bay layover, which is one of the largest staging areas for shorebirds in North America.

Unfortunately, reduced numbers of horseshoe crabs over the years have threatened some species of shorebirds, for example the red knot. Reduced numbers of eggs for these birds to eat means that they cannot refuel adequately for their journey to the Arctic and therefore less are breeding. Red knots are listed as endangered in New Jersey and are currently a candidate for federal endangered species listing.

Since 2000, the Atlantic States Marine Fisheries Commission has enacted catch limits on harvesting horseshoe crabs, and, in 2008, New Jersey issued a moratorium on catching the crabs, both in an effort to help increase shorebird numbers.

Learn More about Horseshoe Crabs and Shorebirds

DRBC's page of horseshoe crab and shorebird links

Volunteer to help scientists count horseshoe crabs and shorebirds on the Delaware Bay:

"Horseshoe crabs and red knots soon to arrive on replenished Delaware Bay beaches" - Article in the May 12, 2013 edition of The Star-Ledger by Amy Ellis Nutt that discusses the effects of Hurricane Sandy on the Delaware Bayshore and efforts to replenish its beaches in time for the arrival of the horseshoe crabs and shorebirds; includes a video and several photos.

"Return of red knot B95 to Delaware heartens researchers" - Article in the May 19, 2013 edition of The Philadelphia Inquirer by Sandy Bauers about tagged red knot B95, aka Moonbird. This little bird, tagged in 1995 and nicknamed after the fact that in his lifetime, he has flown the equivalent of the distance to the moon and at least halfway back, was recently spotted on the Delaware Bay. He is believed to be one of the oldest red knots and his survival is a success story for this imperiled species. Also check out related stories on her Green Space blog.