Red Knot and Horseshoe Crab

Red knot.

Deborah Cramer, whose beautifully titled Pulitzer prize winner, The Narrow Edge: A Tiny Bird, an Ancient Crab, and an Epic Journey, celebrates the courageous — even miraculous — life of the red knot, spoke at the Library Society in Charleston, South Carolina on May 11. It was too far for me to attend, but I heard she spoke to a standing room only crowd! Who would have guessed that there could be such enthusiasm for an obscure bird that appears in South Carolina only briefly in the spring and fall?

Like so much in nature these days, the story of the red knot is bittersweet. In spite of its beauty, courage and endurance, the red knot is under pressure on all fronts. Its primary food source, which fuels a (truly epic) 9,000 mile migration from Tierra del Fuego to the Arctic, is the horseshoe crab egg — billions of them, to be specific.

Red knot birds and horseshoe crab eggs

Delaware Bay has been the historical refueling stop. The red knot’s arrival there is perfectly timed with the annual egg laying of hundreds of thousands of horseshoe crabs. Fishermen in Maryland and Virginia have depleted the population of these crustaceans, “harvesting” (aka “killing”) them for bait to catch eels and conchs. Red knot populations have plummeted as a result — so much so that it was recently listed as a threatened species.

South Carolina, fortunately, banned the killing of horseshoe crabs for bait in the 1980s. Ironically, the motivation was to make more of them available for pharmaceutical use. This is ironic because taking the crab’s blood also causes mortality, only not as severely as using them for bait.

So the good news (sort of), for South Carolina anyway, is that it has become more important to the red knot’s migration and survival. Another interesting point, according to Cramer, is that rice fields are also increasingly valuable habitats. With 70,000 acres remaining, the SC Lowcountry is, for the moment, well endowed with both rice fields and horseshoe crabs.

I urge you to read this op-ed by Cramer in the New York Times. She presents with beauty and urgency the dire circumstances facing shorebirds. We can’t ignore the perils we have created for so many creatures.

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