The American oystercatcher population is recovering following a decline documented a decade ago, a Cape Cod science center said.

A comprehensive aerial survey of the oystercatcher population done last year from Long Island to the Mexico border found the population had increased steadily since 2009.

A coalition of 35 conservation groups formed five years ago to protect habitat and aid recovery. — Lanny McDowell

Ten years ago the harlequin-colored shorebirds were in a decline. Habitat loss and human encroachment were blamed. A survey that year showed there were about 10,900 oystercatchers and that the population was dwindling. In 2009 a coalition of 35 groups from Canada to Texas formed to protect the birds, calling itself the American Oystercatcher Working Group.

The work of the group is coordinated by the Manomet Center for Conservation Sciences. The group includes Martha’s Vineyard-based BiodiversityWorks and Massachusetts Audubon, among others.

An aerial survey of some 9,000 miles of barrier islands and salt marshes from Long Island to the Mexico border completed in 2013 found about 11,200 birds. Survey results were announced late last year at the annual American Oystercatcher Working Group meeting in Wrightsville Beach, N.C.

“This kind of conservation success is extraordinary, especially in the shorebird world,” said Shiloh Schulte, a scientist at the Manomet Center in a news release.

Like piping plovers oystercatchers are migratory shorebirds that nest in coastal areas. And like plovers, their return to the Vineyard is heralded each year as a sign of early summer.

Their distinctive long orange beaks are used for prying open the mollusks that are their primary food.

Other members of the oystercatcher protection coalition are:

Audubon Connecticut, Audubon Louisiana, Audubon North Carolina, BiodiversityWorks, Canadian Wildlife Service, City University of New York, Clemson University, College of William and Mary, Conserve Wildlife Foundation of New Jersey, Delaware Division of Fish and Wildlife, Florida Fish and Wildlife Conservation Commission, Georgia Department of Natural Resources, Gulf Coast Bird Observatory, Manomet Center for Conservation Sciences, Maryland Department of Natural Resources, Massachusetts Audubon, Nantucket Conservation Foundation, National Audubon Society, National Park Service, New Jersey Audubon, New Jersey Division of Fish and Wildlife, New York City Audubon, North Carolina State University, North Carolina Wildlife Resources Commission, Rutgers University, South Carolina DNR, Texas A&M University, The Nature Conservancy, Trent University, University of Georgia, U.S. Fish and Wildlife Service, Virginia Department of Game and Inland Fisheries, Wildlife Conservation Society, U.S. Geological Survey and National Fish and Wildlife Foundation.