by Hugh Markey
If Tierra del Fuego isn’t the end of the earth, it’s pretty close.
The desolate landscape that comprises the southernmost tip of South America has no ports for visiting cruise ships; there are no tourist areas with merchants selling their wares. Mostly, it is home to sheep farmers. And a bird—the red knot—whose migration is one of the longest in the world.
In The Narrow Edge, Deborah Cramer travels from Chile to the Arctic tracing the migration of a bird that is roughly the size of a robin. That migration is also intrinsically tied to the mating patterns of the horseshoe crab, whose eggs form a high percentage of the red knot’s diet. (Both of these animals are regulars along Rhode Island’s shoreline as well.)
Cramer’s travels explore the rise and fall of both populations and the people racing to arrest the downward spiral of both species.
Horseshoe crab eggs, which contain six times more energy than low-fat, high-protein mussels, are easily digestible, according to Cramer, with knots turning as much as 70 percent directly into fat. Such an important food source was nearly decimated in the mid-20th century when horseshoe crabs were collected and used for fertilizer by the thousands. Even taking horseshoe crabs under license for medical research has created controversy.
The horseshoe crab’s copper-based blue blood has been used for decades to test pharmaceuticals before they come to market. While the process of taking the animals to be bled and then returning them to the ocean had been thought to be a safe, sustainable process, Cramer points to new evidence that crabs restored to the ocean may not be as likely to survive and breed as first thought. Researchers have documented confused behavior among crabs returned after being bled, behavior that may last weeks. Cramer charges that not enough research has been done on the effects of such practices to ensure the health of the animals.
Cramer takes the long view in assessing the populations of both species, maintaining that examination of history and of human behavior should set goals for preservation:
The historical abundance of shorebirds and horseshoe crabs … matters. We so easily settle for the diminished world around us, a world that, in terms of the richness and abundance of plant and animal life, may be a mere 10 percent of what it once was. Unaware of what we have lost, we can’t imagine what we might restore, and instead, we argue over how many of the scraps we might still take.
In The Narrow Edge, Deborah Cramer places centuries-old field notes in a greater context of the people and attitudes of the time period from which they came. That historical element is vital to setting contemporary standards of just how much to fight for the survival of both species, and for the ecological vibrancy of the world.