The federal government is moving to protect a group of regular Cape Ann visitors.
The visitors include the red knot, a robin-sized shorebird known for its 10,000-mile migration from South America to the Arctic.
The Fish and Wildlife Service is proposing that the bird be listed as threatened under the Endangered Species Act. Officials say rising sea levels and disappearing habitat along the East Coast are taking a toll on the rosy-breasted bird, which makes refueling stops on Cape Ann, Cape Cod and Delaware Bay.
While the red knot prefers the sandier beaches of Plum Island off Newburyport, the bird is a regular visitor at Rockport’s Halibut Point State Park on its migration , according to Gloucester resident Chris Leahy, the Gerard A. Bertrand Chair of Natural History and Field Ornithology at Massachusetts Audubon.
Red knot populations have dropped by about 75 percent in Delaware Bay since the 1980s, a result of shrinking habitat and a drastic decline in the region’s horseshoe crab population. Crab eggs are a key part of the birds’ diet, which also includes mussels and clams.
The red knot is already listed as endangered by New Jersey and would join the piping plover as East Coast shorebirds protected under the Endangered Species Act.
Shorebird experts have identified 15 other Atlantic Flyway shorebirds that warrant immediate attention, including the American oyster catcher, lesser yellowlegs, ruddy turnstone and whimbrel.
Leahy said that while the American oyster catcher is not a bird you would expect to see on Cape Ann, it has recently returned in larger numbers to the islands of Salem Sound.
Lesser yellowlegs are common on Cape Ann, feeding in the pools of the area’s abundant salt marshes in April and May and again in July through September, Leahy said.
Even more common here is the ruddy turnstone, which likes to feed among the rocks on our shores in May and September; Leahy says some of these shorebirds winter here, too.
Whimbrels are foot-tall sandpipers with a curvaceous bill and a distinctive call that spend July through late September in Cape Ann. Leahy said he hears these birds before he’s sees them around Gloucester’s Brace Cove.
All these once-common coastal species are declining due to threats from climate change, coastal development and hunting, as well as other threats such as oil spills and diminishing food resources, Fish and Wildlife Service said.
U.S. Fish and Wildlife Service Director Dan Ashe called the red knot “an extraordinary bird that each year migrates thousands of miles from the Arctic to the tip of South America and back.” Like many shorebirds, the red knot “is vulnerable to climate and other environmental changes,” Ashe said, noting that steep population declines have occurred in recent years, with much of the decline taking place in the past decade.
More than 100,000 red knots once were common in Delaware Bay, which separates New Jersey from Delaware, but populations have dwindled to about 25,000.
The red knot was one of many species harmed last year by Superstorm Sandy, although officials said the storm played little or no role in the decision to list the bird as threatened.
“I wouldn’t say the listing is particularly tied to Sandy, but (the storm) does underscore or illustrate some of the habitat loss that can be exacerbated by major storms,” said Wendy Walsh, a senior biologist in the New Jersey Division of the Fish and Wildlife Service.
Altered storm patterns due to climate change “may contribute to the threat” faced by the red knot and other shorebirds, Walsh said.
Red knots may also be vulnerable in areas where juveniles spend their first winter away from the Arctic, said Stephanie Koch, biologist for Eastern Massachusetts National Wildlife Refuge. Identifying those locations will enable experts to evaluate if they are protected and secure enough for the species.
Under the Endangered Species Act, plants and animals declared “threatened” are considered likely to become endangered in the foreseeable future. “Endangered” means they are in danger of extinction. The law prohibits a person without a permit from killing, shooting, hunting, pursuing, harassing, capturing or engaging in other activities deemed harmful to the endangered or threatened species.
The proposal to list the red knot and the other birds as threatened likely will be finalized next year.