The Narrow Edge: A Tiny Bird, An Ancient Crab & An Epic Journey.
Deborah Cramer. 2015. Yale University Press.
Would it really matter if we were to lose one bird species? Imagine a species of shorebird or warbler that you see every year, perhaps now in smaller numbers than years past. Now imagine you will never see it again. Sure, you would miss ticking it on your year list, but ultimately how deeply affected would you be by that one species’ absence? What about the extinction of a species of an endemic on some far away island that you will likely never see? Sure, you might briefly note its passing, but would you really care? After all, humans saw the passing of the Heath Hen and Great Auk, and human society marched on. Would that species’ loss matter at all to people who are not birders or ornithologists? What is it worth to you to try and keep those birds from disappearing? What would you be willing to pay or do? As frightening as those questions are, there is little doubt that many familiar species are declining, some at an alarming rate, and that extinction is a real possibility in the near future for a number of bird and other animal species worldwide. These questions are at the heart of The Narrow Edge.
Deborah Cramer is a seasoned writer and journalist and author of several books on natural history. She lives in Gloucester, Massachusetts. Many of us are familiar with the general story of the decline of the Red Knot and that species’ dependency on healthy populations of horseshoe crabs. Cramer’s book, moreover, is a superb piece of fresh field reporting that expands our understanding of the stories of these two species. She follows the knot from Tierra del Fuego north to Nunavut, with many stops in between: Delaware Bay, coastal Argentina, South Carolina, Texas and, most unexpectedly, a laboratory at Massachusetts General Hospital. She is a passionate and indefatigable traveler, tromping through miles of beach in the blazing sun or miles of wet tundra in cold and brutal wind. The Narrow Edge is also the story of the many researchers, scientists, and even birders who are dedicating their lives to monitoring knots and hopefully preserving their populations.
In Massachusetts, we never see large numbers of Red Knots, but we do occasionally encounter small flocks. Small compared to what their numbers once were. There are six “lineages” (subspecies populations) of Red Knots worldwide, with a global population of about one million birds. Every lineage is declining. “There are signs of trouble on almost all the flyways—in Africa and Asia, in Europe and North America.” (p. 27)
In North and South America we have the Calidris canutus rufa lineage. It breeds in the Canadian Arctic, migrates down the Atlantic coast, and heads south to the very tip of South America. The Red Knot is known as Playero Árctico in Argentina and Chile, where it overwinters. More generically, the Inuit of Nunavut refer to Red Knots as siijariaq, or “birds of the beach,” where they breed. The knot’s migratory journey covers a total of 9700 miles one way, with a few stops in select areas to refuel and rebuild fat reserves for the next leg of the voyage. They are airborne continuously for several days at a time, flying nonstop day and night. Their decline began in the 19th century because Red Knots, like many other shorebirds, were hunted for the table.
New York’s luxurious Astor House, whose guests included Abraham Lincoln, listed on its October 11, 1849, menu roasted wood ducks, dowitchers, plovers, mallards, and broiled robin snipe (Red Knot). An article in the June 11, 1887, issue of Good Housekeeping entitled “Table Supplies and Economics: What to Buy, and How to Buy Wisely and Well” praises the offerings in a New York market, which include robin snipe at $1.75 a dozen, smaller yellowlegs at $1.50, and greater yellowlegs at $3.00. Henry Fleckenstein, author of many books on bird decoys, wrote that birds were “hauled from the meadows in wagons heaped full over the boards,” packed in barrels, and shipped by train or boat to city markets. Birds that weren’t as good to eat were used as packing for the others. Not all the shorebirds made it to market. Barrels of knots, turnstones, and plovers shipped to Boston spoiled during passage and were tossed overboard. (p. 69)
The rapid decline in numbers of Red Knots was noted by sportsmen even then, and some speculated on their imminent extinction. The Lacey and Migratory Bird Treaty Acts put an end to the unsustainable market gunning and hunting, but most species of shorebirds never recovered their population levels prior to the 19th century.
Flying there with researchers who monitor knot populations every year, Cramer began her book on the Atlantic side of the Straits of Magellan. For many years, no one knew where knots overwintered. In the early 1980s, Guy Morrison of the Canadian Wildlife Service and Brian Harrington of what was then the Manomet Bird Observatory decided to look for wintering knots by driving south from Buenos Aires along the coast of Argentina, poking into every shore overlook they could find. They did this in a beat- up Citroën. Finally, after thousands of miles and an eventual switch to aerial surveys, they lucked out, and one of the great mysteries of ornithology was solved.
But that was only part of the knots’ story. In order to complete their migratory trip, knots and other shorebirds must stop en route to feed; they lose much weight flying so many miles. In a few days of feeding they have to double their arrival weight. They must find beaches that offer high-energy food like horseshoe crab eggs. One of the most famous stopover spots is Delaware Bay. In the early 1980s, Pete Dunne, Clay Sutton, Wade Wander, and David Sibley discovered the amazing spectacle of an estimated 150,000 Red Knots in a feeding frenzy along with an estimated 1,500,000 other shorebirds in Delaware Bay. Why wasn’t this critical feeding location, so close to well-known birding spots, not discovered until the 1980s? There are records that Delaware Bay had been visited by a number of sportsmen and ornithologists over the past century. Why had no one previously noted the throngs of shorebirds gobbling the horseshoe crab eggs? One suggestion is that no one had gone to Delaware Bay during the narrow window in spring when the knots and other shorebirds are there in peak numbers.
Horseshoe crabs (Limulus polyphemus) come ashore to mate in spring and deposit the eggs that are so critical to the Red Knot. The crabs need shallows in areas along barrier beaches. Over the millennia the northward migratory routes of shorebirds have evolved so that they coincide with the laying of the crab eggs. In 1875, the eggs in Delaware Bay shallows were described as so thick that they could be shoveled up and collected by the wagonload. The numbers of horseshoe crabs have dramatically declined since, and nowhere do we see that many eggs along our shores.
In the 19th and 20th centuries, horseshoe crabs were harvested in large numbers for a variety of uses. Early on, they were collected to feed pigs. Later, they were taken in much larger numbers and used as a commercial fertilizer, Cancerine. Today they are still being “harvested” in large numbers locally as bait for eels and whelk, most of which are exported. To give you an idea of how many horseshoe crabs are taken, in 1999, one Virginia fisherman took 1.4 million horseshoe crabs. Combine these harvests with a loss of shore habitat to human development and the effects of pollution, and little wonder that since the 1960s and 1970s horseshoe crab populations, like the knot, have declined dramatically. Some states have now banned the taking of horseshoe crabs, and in those areas populations appear to have stabilized for the moment. In other states, the unsustainable harvest continues.
Perhaps the most unusual use humans have found for horseshoe crabs is the relatively recent discovery that their blood is the source for LAL, limulus amebocyte lysate. A hidden danger with any medical injection is that the substance to be injected can be tainted with potentially lethal bacteria, leading to what was historically called “injection fever.” It was discovered that the blue blood of the horseshoe crab clots in the presence of gram-negative bacteria and is therefore a fine indicator of these endotoxin contaminants. Consequently huge numbers of horseshoe crabs are now harvested alive by biomedical companies and shipped to various labs where some of their blood is taken. These horseshoe crabs are then shipped back and released into the wild. This practice appears to be a better way to use these ancient invertebrates because we are only borrowing them for some bloodletting. But it has been discovered that horseshoe crabs that have been bled and released are lethargic and do not behave normally for up to six months, a condition that may lead to weakened stocks.
Red Knot in flight. Photograph by Gregory Breese/USFWS (CC BY 2.0).
Cramer’s last stop on her grand tour in search of knots was Southampton Island in the Canadian Arctic in the province of Nunavut, a very isolated spot. Before she could go, she had to be trained to use a 12-gauge shotgun. Polar bears were very much present, and she had to be able to defend herself and others. Cramer joined a small band of researchers and Inuit who were studying a variety of wildlife that inhabited the Arctic tundra. It was very windy, cold, and wet most of the time, and walking across the tundra was physically tough. It was very easy to get lost even a short distance from camp. Knot nests were extremely hard to find, particularly since that bird’s populations had declined. In most seasons researchers found no nests. Still, they kept returning year after year or at least until the polar bears got to be too much of a threat. Global climate change was on everyone’s mind because they could see the first effects of the ice starting to dwindle. It was a wild and sobering end for Cramer’s quest.
There is a chapter in The Narrow Edge in which Cramer attempts to answer the questions I posed at the beginning of this review: “Does Losing One More Bird Matter?” (p. 158). For the rest of The Narrow Edge, Cramer is the clear-headed journalist, professionally reporting from her various destinations, but in this one chapter, she writes with a deep passion. It is the intellectual heart of the book and is a stand-alone essay that encourages every reader to find his or her own answers to grim questions no one really wants to think about.
What is the financial value of that which nurtures the human spirit? And what kind of uneasy moral terrain do we inhabit when, on the basis of financial expediency, we choose which species will live and which will die? (p. 174)
The Narrow Edge is an important book, but is also a fine and fascinating armchair travelogue. Cramer spends time with some very dedicated scientists working long hours to learn more about and hopefully save the remaining populations of knots and other shorebirds. Some of these same scientists have gone beyond their academic pursuits to help local governments preserve pieces of habitat or stop local sources of pollution. I think it is not a stretch to call these scientists heroes. The Narrow Edge is an inspiring and sobering account of how our coastal ecology works, what is wrong with it, and what can be done about it. The lives of the Red Knot and the horseshoe crab, intimately intertwined, are both declining worldwide and continue to face challenges from habitat loss, red tide, pollution, overuse, and ultimately, global warming. Horseshoe crabs are still being harvested in many locations, and Red Knots continue to be trapped and shot along their migratory route in South America. We know what can be done to save both species, and by doing so, to save other species and maybe ourselves. But do we have the will to do so?
Recently I interviewed Deborah Cramer, and I bluntly asked her if she were still upbeat about the future of both species despite the human-caused problems. She was quick to respond that she strives to be an objective reporter and is careful in expressing personal opinions. But in meeting so many dedicated people working on the challenges confronting the knots and crabs, she found hard-won inspiration and hope. And despite the problems mentioned above, both the knot and the horseshoe crab have hung on. She expressed a guarded optimism that future generations will still be able to witness flocks of knots massing in a feeding frenzy to devour horseshoe crab eggs.
The story of the red knot is a story of loss that turns toward restoration and renewal. It is a story of the tenacity and resilience of birds under terrible pressure making long journeys year after year, even as their homes are diminished and their food grows scarce. As we lose our own bearings, their long flights offer a compass. (p. 223)