Silent Seashores

GLOUCESTER, Mass. — AS the spring days lengthen, shorebirds have begun their hemispheric migrations from South America to nesting grounds in Canada’s northern spruce and pine forests and the icy Arctic.

They are among Earth’s longest long-distance fliers, traveling thousands of miles back and forth every year. I have watched them at various stops along their routes: calico-patterned ruddy turnstones flipping tiny rocks and seaweed to find periwinkles or mussels; a solitary whimbrel standing in the marsh grass, its long, curved beak poised to snatch a crab; a golden plover pausing on a mud flat, its plumage glowing in the afternoon sun.

I used to think that sandpipers flocking at the sea edge, scurrying before the waves, were an immutable part of the beach. No longer. This year, as the birds come north, one of them, the red knot — Calidris canutus rufa — will have acquired a new status. It is now listed as threatened under the federal Endangered Species Act. It joins four other shorebirds on the government’s list of threatened and endangered species.

Sadly, it is unlikely to be the last.

As these birds make their long journeys, they face a host of threats. Whimbrels navigating through tropical storms finally make landfall in the Caribbean, only to be shot by hunters. Wilson’s plovers lose their beach nesting sites to development, and their eggs and chicks to raccoons, dogs and cats, whose numbers swell as more people build along the shore. The tidal flats and inlets where knots, turnstones and other shorebirds feed are disappearing as storm surges and a rising sea eat away at the coastline.

Already the loss of shorebirds has been staggering. In the continental United States, more than half were listed on the 2014 State of the Birds Watch List, compiled by the North American Bird Conservation Initiative. Their inclusion means that their small or declining numbers put them in urgent need of additional protection. The number of North American long-distance migrating shorebirds that scientists have tracked has dropped by more than half since 1974, an alarming loss of 12 million birds.

Sightings of ruddy turnstones, for instance, are down by 75 percent. Semipalmated sandpipers are down by 80 percent in their winter home in northern South America. And in Churchill, Manitoba, the nesting season for Hudsonian godwits has been abysmal.

These sturdy birds travel thousands of miles from the Strait of Magellan to reach the west shore of the Hudson Bay in Canada. But they are now threatened by the changing climate, which, according to 2014 research led by Tufts University, presents an increased risk of extinction to nearly 90 percent of North American shorebirds. As the planet is warming, insect populations are peaking up to two weeks before the godwits’ eggs hatch. As a result, many chicks end up starving.

Over the last three years, I have logged over 40,000 miles following shorebirds. Day after day I trudged across the snowy Arctic tundra, looking for ruddy turnstones that hadn’t shown up to nest, and through miles of meadow where semipalmated sandpipers used to lay their eggs. On a quiet island off the coast of Georgia, I followed the delicate tracks of Wilson’s plovers, whose range is contracting and whose numbers are down 78 percent. In South Carolina in 1831, John James Audubon, watching long-billed curlews flying in to roost at sunset, saw several thousand birds. I saw one, in a wildlife refuge starved of sand and disappearing into a rising sea.

About 10,000 species of birds are living today. Scientists estimate that before humans accelerated the rate of extinctions, a bird extinction might happen every 1,000 years. In my own life, at least 19 bird species have become extinct. One shorebird — the Eskimo curlew — may shortly disappear, if it hasn’t already. Hundreds of thousands once flew from the South American pampas up through the Great Plains, and then back through Labrador, gorging on blueberries. The last sighting, confirmed by physical evidence, was in 1963, when I was a young girl.

We have also seen aggressive, dedicated conservation return birds from the brink. The bald eagle, peregrine falcon and brown pelican were all rescued from the ravages of DDT after the pesticide was banned, though their recoveries took 30 to 40 years. Scarcely 20 California condors were alive in the wild before a captive breeding program began in the early 1980s; it now has pushed the bird’s numbers in the wild to more than 200.

It is not easy to address the complex and myriad threats that these migrating shorebirds face along a flyway that spans two continents, but many people are trying. This work involves curbing development along a congested coast; minimizing human disturbance; curtailing hunting in South America and the Caribbean; protecting habitat that is being lost to dredging, redesigning inlets and stabilizing the sea edge; conserving additional land; and finally, carrying out research to understand how a rapidly changing Arctic affects nesting.

I hope I never walk beaches empty of sandpipers and plovers. But it is possible that may happen. In the case of some shorebirds, it is increasingly likely. This is why we must commit the money and muscle needed to give these birds safe harbor. If we do, we just might keep our shores teeming with shorebirds.