Horseshoe Crabs and Red Knots (not)   1 comment

A couple of weeks back, at the invitation of my NJ birder friend, Claus, I drove down to visit a couple of beaches on Raritan Bay.  The plan was to search for horseshoe crabs and the red knots that rely on the crabs’ eggs to fatten up for the annual trip to their Arctic breeding grounds.

Horseshoe crabs are such cool creatures. They look prehistoric and, in essence, they really are. Physically, they are virtually unchanged for the past 300 million(!) years and some scientists feel that they have similarities to trilobites, these days only to be seen in fossil form. They’re also not really crabs but are more closely related to spiders and scorpions. They look intimidating but are harmless.  One set of eyes is visible at the top of the helmet-shaped shell and they have light receptors all around it as well.

On the move, and they're surprisingly quick underwater...

On the move, and they're surprisingly quick underwater...

I remember years ago walking along the beach with some other kids and, coming upon a dead crab, one of the boys said that he would use it as football helmet. Another one basically said not likely and turned it over to reveal the “business side.” We were all slightly revolted and kept going. Alive, if a crab is turned on its back, it can right itself using it’s scary-looking but harmless tail. If you see one upside down and struggling, you can help it by picking it up by the shell only (you can hurt it if you pick it up by the tail) and setting it to rights.

What's left of the business side of a horseshoe crab

What's left of the business side of a horseshoe crab

May into early June is the time of year when they emerge from deeper waters to mate and lay their eggs on the beach. The largest concentration occurs at the Delaware Bay but NJ beaches see their fair share of these busy critters. At same time, red knots have made their way from their wintering territory from as far south as Tierra del Fuego in South America to stop and gorge on the eggs at these beaches. Studies of red knots indicate a serious decline in their numbers, partly due to over harvesting of the horseshoe crabs.

Red Knot at Nickerson Beach, NY, August 2008

Red Knot at Nickerson Beach, NY, August 2008

On our trip last weekend, we saw several crabs in both locations we visited but unfortunately no knots. We figured that they’d already continued on their way north. Quite a few dead crabs littered the beach but others were busy doing their thing at the water’s edge or in the shallows. I learned later that we would have seen a lot more of them had we gone after sundown as the darkness offers them safety while spawning.

"From Here to Eternity" for horseshoe crabs?

"From Here to Eternity" for horseshoe crabs?

We had a good day, nonetheless. On the path through the salt marsh to the beach at Ocean Beach, a bunch of marsh wrens were busily singing at each other. Wrens amaze me; they are so small but so loud! They’re also good at knowing when they have a camera pointed at them and flew away each time I got my lens on one.

I also saw my first Seaside sparrow from a great distance, too far away for my camera’s capability. The usual assortment of gulls scattered around the beach, including Bonaparte’s gulls. Some of the gulls seemed to appreciate the crabs as pedestals in the shallow water.


There was a nice variety of shorebirds in breeding plumage. White-rumped sandpipers were my second lifer of the day and joining them were pretty ruddy turnstones, dunlins, pectoral sandpipers and a willet.

A willet is at the back left, dunlin is just to his right, the smaller birds are sanderlings

A willet is at the back left, dunlin is just to his right, the smaller birds are semipalmated sandpipers

I like how the picture above illustrates the different sizes of these shorebirds. The willet in the back is much larger than the surrounding semipalmated sandpipers.

A nice addition was a pair of Black skimmers at the beach in South Amboy. I’m accustomed to seeing them do their skimming behavior in the ocean off one of the Long Island beaches. Watching them skim in the shallow water so close to shore was an almost intimate experience.


A few more random images from the day are below.  My thanks to Claus and Hadas for letting me tag along with them. I love visiting new places and was not disappointed, despite the lack of red knots. Hopefully I’ll see catch them at the beach later in the summer when they’re on their 9000 mile journey down south.


Another type of bird (Semper Fi!)

Another type of bird (Semper Fi!)




Posted June 22, 2009 by Beth in Bird watching, Nature

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One response to “Horseshoe Crabs and Red Knots (not)

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  1. “From Here to Eternity” for crabs….you made me laugh out loud!

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