No room at the beach

Migratory shorebirds getting muscled out of their coastal stopover spots

Shorebirds are in decline because of development of their fragile coastal habitat. Birds that must migrate up to 19,000 miles can't waste energy evading beach walkers, all-terrain vehicles, or dogs. (Globe Staff Photo / Mark Wilson)

CHATHAM - After the fog lifts, a cloud of short-billed dowitchers, red knots, American oystercatchers and all types of plovers tear and careen off an inlet. They crest on the breeze, settling near the shore.

Beyond the rippling heat and haze, knots and black-bellied plovers roost and preen after a day spent picking water worms from the tidal flats. The helmet-sized carcasses of horseshoe crabs litter the coarse sand, where little sanderlings - among the smallest of shorebirds - exercise their Napoleon-complexes on the bigger birds, starting fights and darting in to steal their food.

This pristine spot where South Beach meets South Monomoy Island is a critical stopover for many shorebird species on their way from the Arctic to their wintering grounds in Central or South America, or even New Zealand.

But such relatively untouched coastal land is getting rarer - and so are the oystercatchers, sandpipers, and plovers that depend on it for their feeding grounds.

The populations of nearly all of North America's 55 shorebird species are declining - including most of the 35 that spend time in New England - in large part because of disturbance to their beachfront habitats. Every flap of their wings to evade beach walkers, all-terrain vehicles, or dogs depletes more of the energy they need for long flights, leading to lower reproductive success and even death, specialists said.

That means that as New Englanders flock to the beaches, they are forcing out flocks of Atlantic shorebird mainstays.

The Shorebird Recovery Project of Manomet is a leader in the effort to reverse the trend. In the last year and a half, the initiative has pooled and focused the resources of conservation groups and governments throughout the western hemisphere and ramped up scientific research on shorebird population trends.

Most shorebirds - a category that does not include waterbirds like gulls or terns - are long-distance migrants. At the extreme, they travel as much as 18,000-19,000 miles twice a year, said Brian Harrington, a Manomet senior shorebird scientist. Their paths usually take them south along the Atlantic coast this time of year and north through the central United States in spring.

They bulk up to twice their normal size for the voyages and fly nonstop for days straight - bar-tailed godwits, for instance, will fly about 40 miles per hour for nine days straight to make the trip from Alaska to New Zealand.

Their movement makes them extremely hard to track - and to help.

"One of the challenges is that these things are just flying all over the hemisphere," said Harrington, one of the godfathers of the shorebird conservation movement. "So to figure out the needs of these birds - sorting out the 'why' - requires this huge geographic understanding of the populations, and nobody really has that."

That's a problem Charles Duncan of the Recovery Project is trying to solve by connecting governments and organizations from South, Central, and North America, so they can complement each other's efforts to protect habitats, manage wildlife and create refuges. The project is based in Plymouth's Manomet Center for Conservation Sciences.

On South Beach last week, Duncan traced a crude map of South America in the sand and made a divot halfway down the coast of Argentina - at San Antonio Oeste, one of the premiere sites of Manomet's Western Hemisphere Shorebird Reserve Network. Just then, a highly endangered red knot banded at that very refuge sauntered past Harrington's telescope.

"Perfect timing," Duncan said.

Those little bands are the best tracking tools available - at least until researchers come up with a radio tracker small enough for tiny shorebirds. By noting where individual birds are stopping on their migration, scientists can gain a better understanding of what is affecting them along their journey, said Larry Niles, wildlife biologist with the Conserve Wildlife Foundation of New Jersey.

"Documenting this is critical, because you can't get groups to act unless you have good data to justify the action," said Niles, a 25-year veteran of the US Fish and Wildlife Service. "But when you're dealing with birds that are moving so much, it becomes very difficult."

To get better data, Stephen Brown, Manomet's director of shorebird research and conservation, is currently in the Arctic National Wildlife Refuge in Alaska, surveying and determining the nesting density of shorebirds.

"We're in the process of building a North American-wide monitoring program," he said before he left. "But funding has been limited and you can imagine how difficult it is to track birds across the arctic."

Five years ago, Brown also spearheaded a monitoring project on the American oystercatcher - striking birds with black heads and bright, orange bills that are some of the few short-distance migrants, traveling no more than 2,800 miles between wintering and breeding grounds. The project provided the first complete survey of the American oystercatcher population, including their wintering grounds, and distribution.

Global warming and rising sea levels may pose bigger problems for the shorebirds in the future, said Brad Andres, national coordinator of the US Shorebird Conservation Plan.

"Even if we've been successful with restoring wetlands, what are they going to look like in 50 years with sea levels rising?" he said. "Some days I sit here and think, with increasing [human] population sizes, and no federal leadership, and [no curb on] consumerism - it's hard to imagine how we're going to do it."

Still, some of the efforts to save the birds, through monitoring and conservation, seem to be paying off.

Out on the mudflats at South Beach - the squelchy terrain smells something like a concert venue bathroom - Harrington, barefoot and wearing a white seafarer's beard, notes the third pair of oystercatchers with a chick he'd seen that day.

"They're doing really good this year," he said. "I think in the last three years, I've seen two."