Horseshoe Crabs and Migrating Shorebirds Partake in Yearly Ritual

Moratorium on Crab Harvest Seems to Be Helping Red Knot Population Rebound
Jun 10, 2015
Photo by: Pat Johnson Around the full moon on the high tide, horseshoe crabs return to sandy beaches to lay thousands of eggs. Last Monday, some battled wind and surf to return to Graveling Point beach in Little Egg Harbor.

Horseshoe crabs and migrating shorebirds have an ancient survival pact that they play out every spring during the full moon in May and June.

The lumbering horseshoe crabs come ashore to mate and then lay their eggs by the millions. Certain long-range migrating shorebirds such as the ruddy turnstones, semipalmated sandpipers and federally-endangered red knots count on feasting on horseshoe crab eggs for the energy they will need to complete their astounding migration from South America to the wilderness plains above the Arctic Circle, where they lay their eggs and raise their young in relative peace.

Locally, horseshoe crabs came ashore at Graveling Point beach in Little Egg Harbor on June 1 and 2 while a fierce gale was blowing. The large females, encumbered by their smaller mates that attach themselves to their shells, were tossed and rolled in the surf until they could get a foothold and struggle ashore. They were met by hundreds of laughing gulls already treading the sand in anticipation of the bounty to come.

Off to the side, a handful of ruddy turnstones waited for their turn at the water’s edge.

Some beach-goers were surprised by a scene seemingly out of Alfred Hitchcock’s “The Birds” and were hesitant to enter the fray, but some children ventured up to their knees in the surf until they saw the prehistoric-looking crabs in the water and ran shrieking to their parents. Despite their looks, horseshoe crabs are harmless.

This small-scale scene of crabs and birds was being replayed up and down the Atlantic Coast, but where it really is astounding is on the Delaware bayside, where the crabs and the birds number in the tens of thousands. On the Delaware bayside, additional participants in the yearly spring ritual are the volunteers from the American Littoral Society, the Conserve Wildlife Foundation and the National Fish and Wildlife Foundation, whose mission is to count the number of migrating shorebirds of concern, especially the red knots. Red knot numbers had crashed in the late 1990s at the same time that the harvesting of horseshoe crabs for bait was at its peak. Then, in 2008, a moratorium on the harvesting of horseshoe crabs was enacted.

Bird numbers did not suddenly increase, but this year was a banner year for red knots along the Delaware Bay.

Wildlife consultant Larry Niles headed the Conserve Wildlife Foundation Team. Volunteers counted 19,077 red knots along the Jersey side of the Delaware Bay, the most seen in the state in a decade. In addition, Delaware’s shorebird team counted 2,000 knots along their shore, bringing the total to 21,077.

This number is almost equal to the three previous yearly counts added together (24,000).

Despite the good news, red knots are still below the recovery target of 80,000, a number that could remove them from endangered status. In 1989, 95,000 red knots were recorded.

In addition, the team counted 12,295 ruddy turnstones on the Jersey bayside and 56,788 semipalmated sandpipers. These numbers were also close to the maximum counts of the recent past.

Shoreline restoration along the Delaware Bay has also contributed to the success rate this year, according to Niles.

— Pat Johnson


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