Natural Events Almanac

Delaware

Horseshoe crabs
ŠJeff Lepore

Event: Shorebird Migration and Horseshoe Crab Spawning

When: May and June

Each spring the world's largest population of spawning horseshoe crabs comes ashore on the beaches of the Delaware Bay to lay their eggs. At about the same time, more than one million shorebirds are embarking on their annual journey from South America to Arctic breeding grounds. Along the way, the birds make a single major resting and refueling stop on the shores of the Delaware Bay. During their brief stay, the birds feast on horseshoe crab eggs along the beach and other food resources in the tidal marshes to sustain them for the remainder of their flight.

On the Delaware side of the Bay, Port Mahon Preserve is open to the public. Milford Neck Preserve is closed to the public, but volunteers are needed to assist at this preserve with the annual horseshoe crab survey on the full and new moon high tides in May and June. In New Jersey Conservancy beaches will be open to the public with special viewing sites available.

For additional information on a particular location, click on the name of the preserve associated with the event or visit the Delaware site.