An excerpt from our Gulf of Mexico field report series
I spent June 24 looking for Wilson’s Plovers under the baking sun on a barrier island east of Grand Isle, Louisiana. I was with a survey team led by Richard DeMay, of the Barataria-Terrebonne National Estuary Program, and Steve Cardiff, of Louisiana State University. We were on the Chaland Headland, a quarter-mile-wide, three-mile-long beach flecked with shells, sprigs of pickleweed, and, somewhere, a few dozen little seven-inch shorebirds the color of sand.
Cardiff showed me the ropes, pointing out three superbly camouflaged pairs as soon as we got off the boat. Slowly my eyes learned how to make pieces of plovers into a whole: the dun-colored triangle of wings and tail; the rounded knee-shape of a head; the white-brown line of the neck.
The plovers were numerous here. Unlike many shorebirds that breed in the far north, Wilson’s Plovers breed on southern U.S. and Caribbean beaches; they spend winters in Central and South America. The Gulf Coast is home to about 60 percent of North America’s estimated 12,250 Wilson’s Plovers, making this species one of the shorebirds most at risk from oil.
These Wilson’s Plovers were nesting on sand-and-shell flats kept dry by virtue of being six inches higher than their surroundings. Males make a few three-inch-wide scrapes in the sand and, if a female finds one she likes, she may lay an egg there the same day. Later, parents may use the other scrapes as decoys to confuse predators.
Though the birds nest fairly far above the high-tide line, they forage in marshes and mudflats. They seize fiddler crabs in their bullet-shaped black bills, shaking off each leg one by one and then swallowing the carapace whole. Their entire foraging strategy lies within the path of oil.
As I walked along the shoreline, I came across a hardened patch of oil about 20 yards long. Waves had shaped it into a pitted shelf and covered the edges with sand. The oil seemed as if, after enjoying a brief release from the earth, it was reverting to geology. But this oil will remain toxic even if it disappears.
Once oil is buried by sediments, there’s not enough oxygen available for oil-eating bacteria to consume it. Burrowing worms and mussels ingest it but can’t process the toxins, so they store them in their bodies. As it moves up through the food chain, this remaindered oil will slowly but continuously work its way back into our world.
It’s a depressing setback for attempts to stem that other coastal Louisiana disaster, the rapacious loss of wetlands that is claiming up to 35 square miles per year. As Cardiff said, “The reason this is called Chaland Headland is because there used to be marsh all the way up here. This wasn’t an island until recently.”
To fight the decline, workers pile dredged sand on vanishing beaches, spread it with bulldozers, and then plant beach vegetation to hold it in place.
It was this beach-building, not the oil, that prompted DeMay’s and Cardiff’s surveys. They conduct monitoring surveys, as budgets allow, so they can understand whether beach restoration helps birds like Wilson’s Plovers and Least Terns. Like most monitoring work, it’s chronically underfunded: the survey team is at least half volunteer and relies on DeMay’s ability to free up boat time (most beaches are inaccessible by car).
The pricelessness of monitoring data is never apparent except in hindsight. To understand a catastrophe, we need to know what happened leading up to it, not just what happens afterward. It’s why banks have security cameras and airplanes carry black-box recorders. Without ecological monitoring of each ecosystem we care about, the answers we need will stay as hidden as a Wilson’s Plover in the sand.
A Cornell Lab team visited Louisiana from May 31 to July 20 to film the region’s wildlife and oil’s effects. Read more about our work and view photos at our blog.
Originally published in the Summer 2010 issue of BirdScope.
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