The Narrow Edge
By Deborah Cramer
Yale University Press, 2015.
The “narrow edge” in the title of this engaging book by Deborah Cramer evokes the image of comedian Harold Lloyd, in the 1923 film Safety Last!, teetering on a skyscraper ledge, clinging for dear life to the hands of a clock. It is an apt metaphor for the uncertain future of the red knot (“a small sandpiper about the size of a robin and weighing about as much as a coffee cup”), which roams the sliver of sand between land and sea, a precarious place to be these days. This indefatigable bird lives for five months on desolate tidal flats at the tip of South America, then, as if possessed, travels 9,500 miles north, following the coasts of two continents, to breed in the Arctic.
In The Narrow Edge: A Tiny Bird, an Ancient Crab, and an Epic Journey, Cramer explores this flyway by plane, kayak, helicopter, and foot, feeding on history and science as she goes, wrestling with the consequences of human interaction with the natural world. Her journey ends at a scientists’ field camp in the most northern of Canada’s territories, where the red knot lays its eggs. The birds arrive with just the feathers on their backs, while Cramer is weighted down with supplies, bulky clothes, a GPS, and the requisite twelve-gauge shotgun to ward off polar bears. It was the worst summer for shorebirds in the field camp’s history.
In her travels, Cramer often sustains herself on pilot biscuits, but the red knot needs high protein fuel and lots of it, preferably the eggs of the homely horseshoe crab. Yet this living fossil, which has survived on Earth for half a billion years, is running out of breeding grounds. The beaches on which it lays its eggs are being destroyed from over-development, rising waters, oil spills, and industrial run-off. As if the crab didn’t have enough to worry about, it is also of considerable value to humans: Aside from its historical use as fertilizer and bait, the crab’s blue blood is used to ensure the safety of intravenous medical procedures. In theory, the blood harvest should not kill the crab, or at least not many, but Cramer’s research suggests another story—and so the red knot’s fortunes rise and fall with the crab’s.
Cramer walks and talks with a wide band of scientists and naturalists who are working against the clock to save the red knot, because if this shorebird disappears, it won’t be the only one, and we cannot predict the consequences. “The foundation of food webs may not be apparent until they fray,” she writes, citing the disappearance of the passenger pigeon with the rise of Lyme disease. (Read the book to discover the connection.) When an extinction occurs, there is no way to know which species will be the next to cling to the hands of time.
Originally published in Orion Magazine, September/October 2015