The lives of two unlikely creatures — an ancient "living fossil" called the Horseshoe Crab and a delicate shorebird called the Red Knot — are intimately intertwined.

The Delaware Bay is the largest spawning area in the world for the ancient Horseshoe Crab. Every May, the Horseshoe Crabs come to Delaware Bay beaches to lay their eggs. At the same time, shorebirds — especially the endangered Red Knot — use the Delaware Bay beaches as a food stop on their annual migration from South America to the Arctic. They feed on the Horseshoe Crab eggs until they have enough energy for the final leg of their flight north.

Red Knot Photo ©2005 Don Chernoff

Lawrence Niles, Ph.D., chief of the Endangered and Nongame Species Program of the New Jersey Division of Fish and Wildlife, says the Delaware Bay is the last stop for the Red Knots en route from their winter home in Brazil to their summer home in the Arctic. "The birds arrive at the Delaware Bay beaches at very low weights," he said, "lower than at any other stopover. They have to double their body weight,and the only nutrient they can use is Horseshoe Crab eggs."

But Horseshoe Crab populations have been declining over the last decade due to over-harvesting. As a result, Red Knot populations are also declining rapidly.

The decline in Red Knot populations has chiefly been caused by the lack of sufficient eggs for foraging birds on the Delaware Bay. Prior to the over-harvest of horseshoe crabs, the Knot weight rate increase here was the highest in the world, recorded at nearly 9 grams a day in the late 1990s. The rate declined to a low of 2 grams a day in 2002. Low weight gain rates results in fewer individuals reaching the arctic breeding grounds and higher adult mortality.

Where To Observe

Two of the best sites to observe this incredible phenomenon on the Delaware Bay are Port Mahon, east of Dover Air Force Base, and the DuPont Nature Center at Slaughter Beach near Milford.

The best time to observe is in the evening, near the full and new moons of May and early June. Be sure to follow good conservation and birding etiquette. Do not go onto the beaches, or in any way disturb the Horseshoe Crabs or shorebirds. Staying in your car will act as a blind and allow everybody to see the birds, without disrupting the natural processes.

Actions To Save These Threatened Species

To save these threatened species, Delaware Audubon supports a moratorium on Horseshoe Crab harvesting on the Delaware Bay.

Delaware enacted a two-year ban on horseshoe crab harvesting, which would have become effective January 1, 2007. However, on June 9, 2007, the Superior Court of Sussex County overturned the moratorium. The Department of Natural Resources and Environmental Control (DNREC) has chosen not to appeal the decision.

The Delaware Audubon Society, along with the Delaware Riverkeeper, New Jersey Audubon, and the American Littoral Society, appealed the Superior Court decision to overturn the moratorium. The Superior Court denied our petition to appeal. We now have appealed this decision and the decision to overturn the moratorium to the Delaware Supreme Court—where the matter is still pending.

Delaware Audubon along with these and other co-plaintiffs, including the American Bird Conservancy, Defenders of Wildlife, National Audubon and others, previously filed a lawsuit against the US Fish and Wildlife Service under the federal Administrative Procedures Act (APA) and the federal Endangered Species Act (ESA) for failure to perform an emergency listing of the Red Knot. This matter is currently pending in the federal courts.

In October 2007, DNREC issued new amendments to its Horseshoe Crab Regulations. The current rules prohibit the harvest and landing of all horseshoe crabs in Delaware from January 1 of this year through June 7, 2008. They allow the harvest of 100,000 male horseshoe crabs from June 8 through December 31 of this year. In 2008, beach collection of male-only crabs will be allowed Monday through Friday, June 8-June 30, from Port Mahon and private beaches where collection is currently legal. Harvest and landing of female Horseshoe Crabs is prohibited for two years.

In March 2008, New Jersey Governor Corzine signed a law establishing a two-year moratorium on Horseshoe Crab harvesting in NJ.

• Read Delaware Audubon's statement in support of a Horseshoe Crab moratorium [PDF file].
• Visit the Delaware Birding Trail website.
• Read more about Delaware Audubon's efforts to save the Red Knot in our Spring 2008 newsletter [PDF file].

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This page was last updated on May 4, 2008.