Rare Shorebird: Book Profile of Great Journey and Crab Relationship

The red knot shorebird, a robin-sized, rust-colored sandpiper, is currently in the midst of its fall migration toward South America. Flying from the top to the bottom of the Earth twice each year, the bird feeds on fat to fuel all that movement: Its primary foods are horseshoe crab eggs (in spring) and tiny clams.

For that reason, red knots' wellbeing is also tied up with the success of horseshoe crabs, as a 2011 study led by the U.S. Geological Survey said.

Red knots' wellbeing isn't what it once was, either. In December 2014, they were designated a Threatened Species by the U.S. Fish and Wildlife Service, under the Endangered Species Act. Along the migration route, the birds can be seen in Delaware Bay, a saltwater lagoon in Texas, South Carolina and a few other spots on the United States coast, as the U.S. Fish and Wildlife Service notes.

In her book The Narrow Edge: A Tiny Bird, An Ancient Crab & An Epic Journey (Yale University Press 2015), Deborah Cramer talks about the importance of wildness and having followed the migration of the red knot from its northern summer location in the Arctic's Southampton Island, all along the route to their northern winter home on the Strait of Magellan, just to the north of Tierra del Fuego in South America. On the way, she meets biologists, birders, high school students and others who deeply care about these small birds. Cramer notes that they are "doing service that, rooted in science, springs from and is held by love."

Amid the book's well-researched science, she observes that in its lengthy route, the red knot has an unerring instinct to land on individual beaches with the most plentiful food and "unites us along the shore of two entire continents, following a route that doesn't recognize our boundaries."