Living on the Edge

“Does losing one more bird matter?”

This question was asked by author Deborah Cramer in her book The Narrow Edge: A Tiny Bird, An Ancient Crab, and an Epic Journey.

(Image via amazon.com)

In The Narrow Edge, Cramer explores this question through documenting the journey of the Red Knot, a tiny shorebird. She focuses on Calidris Canutus rufa, one of the six subspecies of Red Knots worldwide. The rufa species uses most of the Atlantic Flyway for their migration route from South America to the Arctic. It’s an extremely long journey – around 19,000 miles round trip- and a dangerous one. Cramer sets out to learn about the obstacles the Red Knots face by traveling the migration route with them.

The journey begins on the beach of  Bahía Lomas in Tierra del Fuego, located at the southern end of South America. She refers to this place as the first “rung on the ladder” for the Knot’s epic migration. From the start, the population of rufas is lower than in the past. They continue up the coast, briefly stopping in Brazil to refuel before landing in Delaware Bay.

A Red Knot at Delaware Bay (Image by Bill Dalton via conservewildlifenj.org)

Although our trip started with Red Knots, there is another creature involved. Enter the horseshoe crab. Considered “living fossils” by some, they have changed very little in the last 445 million years. Red Knots rely eating the horseshoe crab’s eggs to help them complete their migration to the Arctic. However, horseshoe crab populations on the East Coast of the United States have been decimated over the years, due to being used as bait, fertilizer, and for biomedical research.

Horseshoe crab’s blood is copper-based (and therefore blue), as opposed to our iron-based blood. Scientist learned that horseshoe crab’s blood is highly sensitive to endotoxins. Amebocytes from their blood is used for the endotoxin  detector LAL (limulus amebocyte lysate). Humans rely on the crab’s blood to make sure medicines and devices such as IVs are free from harmful bacteria.

© Hans Hillewaert via wikipedia.com

Delaware Bay use to overflow with horseshoe crabs and shorebirds, but the last few decades have been much quieter. Cramer discovers this is having an impact on how many shorebirds make it to the Arctic, a region already threatened tremendously by climate change. Cramer spends 3 1/2 weeks with a team of scientists tracking shorebird nests in the Arctic, then heads back south to James Bay, Ontario. This is where she ends her migration trip, but journey continues for the Red Knots.

Red Knots and Horseshoe Crabs in Georgia (Image by Brad Winn, Manomet via shorebirdscience.org)

The Narrow Edge is a fascinating book. Cramer presents the struggle of the Red Knots and horseshoe crabs by combining history, scientific evidence, and personal stories (from herself and other). She doesn’t just focus on Red Knots and horseshoe crabs, however. When she asks if losing another bird matters, she reminds the reader that every species is interconnected, a notion that many humans tend of forget.

She goes on to say, “The loss of a bird can reverberate through a food web, touching its many strands in ways we have only begun to measure.”

The loss of any species, whether or not they are birds, can have a negative impact on the rest of the ecosystem in which it lives. So many animals and plants in the natural world are living on the edge, just like the Red Knots and horseshoe crabs that Cramer writes about. She brings up many ecological and conservation issues, such as the value of the natural world to humans, ocean acidification, global warming, and habitat loss. The solutions to these problems are complex, and although Cramer alone cannot offer solutions, she presents what we already know and what is currently being done.

Cramer wants us to remember that humans are interconnected with nature as well.  Our actions do have an impact on all forms of life, from the Red Knots to the tiniest insects to the largest mammals. Although the stakes are high, horseshoe crabs and Red Knots continue to persist the best they can. Through Cramer’s cautious warning, there is a glimmer of hope. If conservation of all life becomes more of a focus, maybe someday we can persist like the Red Knots and create a healthier Earth.

(If you want more information about the Red Knots and climate change in addition to the book, you can check out an article written by Deborah Cramer for the May/June 2016 issue of Audubon Magazine. It’s called Red Knots are Battling Climate Change- On Both Ends of the Earth.)