Annual Pilgrimage to the Delaware Bay in May

May 2013. I am pulled here every year in May, to the western shore of Delaware Bay not far north of its mouth at Cape Henlopen, to Mispillion Harbor, where the Mispillion River and Cedar Creek merge in a small estuary, and flow into the bay.  They were here again last weekend, as they always are in May, the mating horseshoe crabs and migrating shorebirds.  As they have always been for millennia, for as long as humans have been on this continent, since the last ice age, and maybe much before that. No one really knows the age of this ancient ecological dance between the birds and the horseshoe crabs. And some psycho-ecological force draws me into this old dance every year also, mine as strong a compulsion as their respective urges. Is there a “unified field theory” that explains the evolutionary imperative of the spawning crabs, migrating birds, and curious humans?

Bruce Byers Consulting

Spawning scrum of Limulus polyphemus, May 2013

Digging back in time in my archive of journal entries and photos, I found a montage of horny crabs, restless birds, and a curious naturalist, reaching back twenty years.  I was somehow reminded of a book whose title has always resonated with me: Steps Toward an Ecology of Mind, by Gregory Bateson. Bateson was a polymath anthropologist and systems thinker, first husband to anthropologist Margaret Mead.  It is more the idea contained in the title than any content that I remember clearly: the idea that context, relationship, process, change through time, evolution – “ecology” writ large – is not confined only to ecological systems, but to human cultural and psychological systems too.  And that in fact ecological and psycho-social systems are connected in space and time, in an evolutionary sense.  Maybe somehow in that “ecology of mind” I might find the “unified field” that pulls us all together at the Delaware Bay in May?  It all started to swirl in my mind like the water, tides, winds, crabs, and flocks of birds…

Here, in reverse chronological order, is an eclection of impressions stretching from 1994 to 2013:

Bruce Byers Consulting

Shorebird mix, Mispillion, May 2009

May 30th, 2013.  As usual, it was different than last year, different than all past years, unique, and yet the same old story.  A very old story.  Apparently the red knots never showed up at Mispillion Harbor in usual numbers.  We heard only vague rumors and hypotheses from the staff of the DuPont Nature Center there: maybe some peregrine falcons hanging around scared them to the New Jersey side of the bay; maybe some are overwintering in Florida or Georgia rather than Argentina; the shape of the sandspits and mudflats at Mispillion hs been changing over the years; maybe it’s climate change. There were a few knots sprinkled among the turnstones, dunlins, semipalmated sandpipers, and dowitchers on the day we paddled at Mispillion. As usual the crabs were jumbled in a mating frenzy.

Bruce Byers Consulting

The bright new DuPont Nature Center at Mispillion Harbor, May 2013

May 15th, 2006.  Went to the Delaware Bay on Saturday, to the mouth of the Mispillion River, to witness the annual spring spectacle of migratory shorebirds, which stop there for only two weeks on their incredible migrations between winter feeding areas on the shores of Argentina, Brazil, and Chile, and their breeding grounds in the Arctic. The birds come because of the food source provided by the eggs of horseshoe crabs, Limulus polyphemus, which spawn at the May full moon.  These evolutionary survivors predate flying insects, and the dinosaurs, now extinct; they have hardly changed in 350 million years.  Each year the experience is different – different weather, a different mix of shorebirds, different timing of moon and tides and water temperature.

May 2002.  What an ecologist does for fun:  yesterday I went to a beach on the western shore of Delaware Bay in the state of Delaware, facing across the twenty-mile-wide bay to the lower peninsula of New Jersey.  It was ten o’clock at night, dark. The tide was nearly high on the narrow sand beach.  A breeze off the water keeping the mosquitoes back in the salt marsh behind the beach, gentle waves licking the sand, a full moon low and yellow in the southeastern sky, through thin clouds.  By 10:30, as the tide crept in the last few meters, a line of dark round shapes the size of soccer balls formed behind the waves, most visible when looking toward the moon and it’s bright reflection on the water.  These were “horseshoe crabs,” a strange marine creature related to crabs, spiders, lobsters, and shrimp – but these have not changed much in appearance for something like 350 million years, a very durable invention of evolution.  Their shells or carapaces are flattened discs,  like the hubcaps of cars, or ancient Greek masks.  They are about a quarter of a meter across, and the “crabs” weigh about two to three kilograms.  At the full moon in May, when the waters of the bay are warm enough, and the tides the highest they will be all month, hundreds of thousands of these creatures come to the highest tide mark on beaches to spawn, the females lay thousands of eggs in a shallow “nest” scraped out of the sand, and the males crawl over them, dumping sperm into the water.  There are piles and swirls of crawling horseshoe crabs in the warm waters edge, and the waterline develops a frothy foam with all this sex going on.

During the day, the beaches are thick with horseshoe crab eggs that have washed out of the nests of the previous days.  Migrating shorebirds, such as sandpipers, turnstones, and red knots, time their migration to stop here at exactly the right time for this feast.  So, today, I saw thousands of little birds feeding on these beaches.  Many spend the winter in Argentina, Tierra del Fuego, Chile – then, after stopping here and a few other places to feed and fatten on the way, they go to the shore of the Artic Ocean to nest during the northern summer.  I read that one of the red knots seen here this year had colored bands that were put on it in Chile.

Bruce Byers Consulting

Lounging by the canoe in the Mispillion salt marsh, May 2010

May 2000. The Mispillion River, winding through marshland from the north, and Cedar Creek, coming from the south, join at the Mispillion Light. Old ramshakle lighthouse surrounded by low, flood-tide flooded sandy ground, rusty trailers, strange shacks, run-down docks, pilings askew. Big cranes and barges on a spoil island where they’re rebuilding a breakwater/barrier island just out from the light, breached by the river. A few people around, a few boats tied up. But a strange, on-the-brink, rusty, flooded, almost-washed-away feel to the place.

Among all this human chaos were tens of thousands of birds! On the spoil island just in front of he cranes and barges the sand was standing-room-only; red knots primarily; then, at the water’s edge, feeding out belly deep, dunlins; some turnstones, especially on the gravelly places, their beak-flicking made the rocks fly. Lots of semipalmated sandpipers; some least sandpipers, plump sparrow-sized “peeps.” Lots of laughing gulls mixed in with the shorebirds, their blood-red mouths striking against black heads when the call.

We put in the canoe just up Cedar Creek from the mouth, and paddled past the chaotic docks, avoiding the wakes of cabin cruisers and a few bigger coastal launches. Drifting in the tidal current past the shore full of birds, we discovered they were completely oblivious to us. We could drift within ten feet, eight feet, of the shorebirds before they seemed looked up from their feeding frenzy and other preoccupations to notice us, and move off a little. Over the millennia there must not have been much danger approaching from the water as far as these shorebirds are concerned. Gulls were a little more wary. In some places little pockets of birds were bathing, and flapping wings vigorously to dry.

We wanted to be careful not to scare are the birds away from their feeding. They are on a tight schedule here, having to rebuild fat stores quickly before flying on to their breeding grounds. Any extra energy and effort needed to rebuild their fat reserves can mean death, or unsuccessful breeding.

We crept around the shore and grabbed a cable hanging off the side of a huge, rusty dredging barge, and watched the scene – thousands and thousands of birds, just ten or twenty yards away. The shallows between us and the island were acrawl with horseshoe crabs. Backs bobbing and slowly rolling reminded me of hippos. Sharp tails would poke out of the water from time to time. Below the surface, a mating frenzy. Above, a raucous feast.

After soaking in the sounds and sights for a long time, we paddled up the Mispillion a little, against the tidal current, and up a sunny black marsh gut. On one side, at eye level from the canoe, a shiny mudflat with a scattering of least sandpipers and an occasional willet, crisscrossed with the tracks of mud snails. On the other, a sandy shore, the inside of the barrier island. Here were knots and dunlins, a few black-necked stilts with their outrageous red legs, and a flock of black skimmers resting on the sand. Occassionally a flight of the skimmers would come in low over the canoe, and start their amazing feeding flight beside or just ahead of us, long, lower red bill furrowing the water and occassionally snapping shut on some unseen (by us) prey, long wings pumping strongly as they skimmed up-current.

Bruce Byers Consulting

Crowd of birds, mostly red knots, May 2009

We came into the sandy shore, birds scurrying away from the canoe as we beached. The waterline was awash with the greenish eggs of the horseshoes, caviar for the shorebirds. When we stepped out, they hustled away. Up in the dune grasses it was warm. The grass full of feathers, combed from the breeze downwind of preening flocks. The sand completely tracked with bird-feet of all sizes. The bare warm sand toward shore from the grasses was littered with horseshoe crabs, who had crawled out to nest during last night’s high tide, most flipped upside down and eaten out by gulls, some still struggling and kicking. My kids tested them all, and “saved” all the live ones, returning them to the cooling water, where they crawled into the mucky water with a “thank you” wave of their sharp tails. A smell of crab, bird, marsh was pungent, but subtle on the breeze. Soon the birds were back, filling the beach and flats in front of us as when we were on the water.

The dunes were a great place for lunch, watching the flights of thousands whirl over, roll and turn, and land on the flats between us and the crazy chaos of wharves, cranes, and shacks at Mispillion. While we ate, the birds came back to the nearby beach where our canoe was pulled up on the sand. The flocks flowed, pecked, and scurried all around this new water creature on their beach, unconcerned. Looking south down the shore with binoculars I saw clouds of birds layered against each other at different depths, swirling and winding different directions. Watching the patterns of the flocks was hypnotic, almost like watching the shapes in clouds.

This spring rendezvous here, in this place, links horseshoe crabs to several species of shorebirds. The crabs have been wallowing along these shores, though perhaps not this place in space, for some 350 million years. Now Delaware Bay has the greatest concentration of horseshoe crabs in the world. But these crabs also came to these shallows in the warming waters of spring, carried by the high tides at he full moon of May, and wallowed in ecstasy when there was no Delaware Bay. They rolled and clambered on the shores of Pangaea, and of Laurasia, before there was an Atlantic Ocean, or a North American continent. And they mated here in their millions before there were birds to feast on their eggs. That’s how old their evolutionary lineage is.

And the birds. No one knows, of course, how long birds have been migrating between North and South America. But they are programmed to be here, in this place, for ten days or two weeks. They come at the exact time when the drabs are mating, when there is a feast of eggs. A rendezvous programmed into the genes of these knots, turnstones, and sandpipers just as it is into the crabs. What is their perception of each other? Do the crabs “care” that their eggs are eaten by these birds? Do the birds recognize the crabs as the source of their life, and say thanks? This place, for the birds, is a rendezvous in evolutionary space-time. And what about for us?

The sound of thousands of wings whirring just feet over your head as you nap in the warm sand is a calming sound. The wings, and warm sun carry off all worries and attachments. As we loaded the canoe, two jet ski-doos, like marsh motorbikes, came buzzing down the Mispillion, one day-glo green, the other day-glo purple. The driver of each was a sunburned young male, and one or two equally sunburned females rode behind. Their outfits were as loud as the jet skis. One driver had an irritating laugh, lubricated with ethanol, I guessed. When they saw us ashore, they decided to stop too; as they farted up to the beach, the whole area cleared in the whoosh of twenty thousand wings. I wondered, when that cloud of birds took off, how many would not make it to the Artic because of these jet skiers. While the girls watched from the beach, the men raced the infernal machines up and down, and cut circles in the still water where the skimmers had formerly been feeding, showing off in a blaze of speed and noise.

All morning long, a backdrop to the clouds of birds, huge C-5 “Galaxy” military cargo jets circled and whined, practicing touch-and-go landings and takeoffs at Dover Air Force Base. Off in the bay, in the haze, a parade of ocean-going ships heading for Newark, Trenton, Philly – the industrial heart of the east. A bulbous-nosed supertanker; container ship; a grey naval cruiser.

Eighy percent of the red knots in the world stop here on their way to the Arctic each year. An oil spill would be a disaster if it happened just at this time of year. Along the shore two pairs of oystercatchers, bright red-orange beaks and black and white bodies, defended their side of a territorial boundary from the other pair with ritualized bowing, pecking, calling, and chasing.

Gautama, the historical Buddha, said: “Life is suffering.” He didn’t mean “it’s all bad” – or even that there is anything wrong with life at all. What he meant was, “Don’t get attached to all this, because it will change. Always has. And if you get too attached, you might forget to notice how incredible, how incredibly beautiful, it is!

Bruce Byers Consulting

Limulus watching us, May 2013

May 1994.  It’s May, when the pulls, tugs, and urges of spring on an old Earth reach deep into the genes of her creatures. Hundreds of millions of years deep, in some cases. On the shores of nearby Delaware Bay in late May occurs a spring ritual, a spectacle, a rite of passage that shouldn’t be missed.

Delaware Bay is prime habitat for one of the strangest-looking and most remarkable creatures that you could ever expect to see — the horseshoe crab, Limulus polyphemus. It looks like it just crawled out of the murky depths of time, and indeed it has, in a way. Horseshoe crabs resemble trilobites, and have been called “living fossils” because they have scarely changed since the Devonian, 350 million years ago. (Although called “crabs,” these creatures are more closely  related to spiders and scorpions than to true crabs; they were called “sea spiders” by early settlers.) Though they may look ancient, they must be doing something right. They are perfectly adapted to survive in the environment of Delaware Bay, as they do by the millions. (Perhaps there’s a lesson in this somewhere, blown about as we are by the winds of change, fashion, and “progress;” buried in the information explosion; future-shocked, and barely muddling through…)

Delaware Bay is crawling with Limulus polyphemus. In fact, it has the largest concentration of horseshoe crabs in the world. When the water warms enough in late May, at the very highest tides, the so-called “spring” tides that correspond with the full or new moon, millions of horseshoe crabs swarm ashore to mate and lay eggs in the sand, a reproductive behavior similar in many ways to that of sea turtles. Females may be a foot across, the males slightly smaller, and with their domed carapaces they even look something like turtles as they swim ashore in the moonlit surf.

Their eggs will not hatch until the tide next reaches them, two weeks later. In the meantime, a feast is spread. The invitation to this feast, part inherited urge and part migratory tradition, reaches across hemispheres, and more than a million shorebirds descend on the beaches of Delaware Bay all at once.

They fly from wintering areas all over South and Central America; from as far away as Tierra del Fuego and Patagonia, and the coasts of Argentina and Chile, some flying a thousand miles or more at stretch. They arrive on the Delaware’s shores hungry and exhausted. By the time they reach the bay, many have already lost up to half of their body weight, and are only halfway to their Arctic breeding grounds. Semipalmated sandpipers, red knots, ruddy turnstones, and sanderlings are the predominant species seen, but twenty or so others also take part in the feeding frenzy. Up to a hundred thousand birds may gather on a few hundred yards of beach.

Each female horseshoe crab lays up to eighty thousand transparent, olive-green eggs. It has been estimated that each bird must eat one horseshoe crab egg every five seconds, 24 hours a day, for two weeks in order to gain back enough weight to continue to the Arctic (for some species, that means a 3000 mile non-stop flight)! That’s almost 25,000 eggs per bird, about one-fourth of the reproductive output of a pair of horseshoe crabs. with more than a million birds and millions of crabs, the math must work out. Delaware Bay is the only place where such a concentration of shorebird food can be found along the entire east coast. It is the largest spring staging area for these birds in all of eastern North America, and the second largest on the entire continent — only the vast Copper River Delta in Alaska hosts more shorebirds each spring.

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About Bruce Byers

Bruce Byers Bruce Byers is an ecologist, writer, and international ecological consultant. His creative nonfiction writing tells stories of science and conservation from around the world. As an independent consultant, he assists government agencies, NGOs, and the private sector in the United States and worldwide with strategies for conserving biodiversity and improving the human-nature relationship.


  1. Carlos Rivas
    June 17, 2013 2:45 pm

    Greetings Bruce¡ It is very interesting to learn about you and your works. Also, these messages are excellent.

    I am working for my own business, Agroforsa. I have 8 partners who use to be retired profesionals, like Felipe Manteiga USA citizen retired from USAID; Dr. Roberto Arias, retired from FAO, Alberto Rodríguez, retired from the Peace of Corp, Carlos Aquino, former Minister of Agriculture and during 10 years general Director of IICA and Pedro Breton, former Senator and Minister of Agriculture; Allen Turner to whom you know very well when he was working for ARD Tetra Tech. Also the Former President of DR, Hipolito Mejía is one outstanding partner.

    As you are working as independent consultant, there exist the possibility for working together if there appear an oportunity. So it is important to have your CV. Best Regards.

  2. It’s A Strange Courage You Give Me, Ancient Crabs | Bruce Byers Consulting
    June 19, 2013 3:12 pm

    […] it “eco-poetic license.” Here is a sequel to my last story, “Annual Pilgrimage to the Delaware Bay in May.” Continuing the “ecology of mind” theme, these are more imagistic and poetic reflections of […]

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