Delaware Horseshoe Crabs

While my interest in natural history has added very little to my sum of achievement, it has added immeasurably to my sum of enjoyment in life. — Theodore Roosevelt


Horseshoe crab eggs are a critical food source for migrating birds.

Every year a major ecological happening occurs along the shores of the Delaware Bay in Delaware and New Jersey:  Thousands of horseshoe crabs gather on the shores to breed.  Well, OK… but I really don’t care about a bunch of ugly, horny bug-like things that look like they crawled out from under something.  What makes this ecologically important? The eggs they lay are food for thousands of migrating birds, many of them major long-distance travelers that travel from South America to the Arctic.  Without this food source along their migration route, thousands may not make it to nesting areas.  Populations of horseshoe crabs, and therefore their eggs, have been decreasing due to habitat destruction and the capture of tons of the crabs (which aren’t really crabs, but are more closely related to spiders and scorpions) for bait by crabbers, who crunch up the horseshoe crabs to capture the much more lucrative blue crabs; they are also used as fertilizer.

The peak of spawning on the Atlantic coast occurs in Delaware Bay where thousands of crabs arrive on the sandy beaches in May and June. Delaware Bay provides an excellent spawning area for crabs because the sandy beaches are protected from harsh wave action. HorseshoeCrabs_D8E0491The beaches’ sand and pebble mixture is perfect for incubating horseshoe crab eggs. Crabs arrive on the spawning beaches during the high tides of full and new moons when the water rises highest on the beach.

HorseshoeCrabs_D8E0593I had time to check out 3 beaches:

– Kitts Hummock (3073 Kitts Hummock Rd, Dover, DE 19901; 39.102715, -75.402319).
– Pickering Beach (Pickering Beach in Delaware often has the highest densities of horseshoe crabs. In 2007 researchers counted a whopping 27 horseshoe crabs per square meter at Pickering Beach during the peak of spawning season (May-June) at high tide.  The beach is off Route 9 on conveniently named Pickering Beach Rd (Route 349). North of Kitts Hummock. (Clean Porta-Johns available 2015).
– Slaughter Beach, which is well-marked on the map and the furthest south of these beaches (real bathrooms available).

Port Mahon, east of Dover, may have been the best bet for birds, but we didn’t make it on this trip.  While the crabs are best closest to high tide, the birds tend to get better as the tide goes out and the eggs are exposed.

The long pointy tail is NOT a stinger and not dangerous.  It helps the clumsy crabs turn right side up when they are inverted in the waves.  The crabs are completely harmless and eat worms and shellfish they find along the bottom of the Bay.

A two hour trip from Baltimore, in season this is a great day trip for nature photographers and families that want to explore nature.

Update 6/10/15

Latest issue of the Nature Conservancy’s magazine says that rufa subspecies of the red knot, a bird that depends on  horseshoe crab eggs to refuel for the 18,000 mile round trip from Tierra del Fuego in summer to the high Acrtic is now listed as a threatened species.  I noticed this year that there were mostly gulls feeding on the eggs — in a past visit there was far more diversity at the feeding frenzy.