MARION – At the mouth of Sippican Harbor in Buzzards Bay, three miles off the shore of this quaint town, the ocean slowly encroaches on tiny Bird Island.
And as the sand gives way to salt marsh, a crucial nesting ground for the endangered roseate tern slips away, bit by bit.
The black-capped, fork-tailed birds could find a reprieve in a $3.77 million plan to restore the 1.5-acre island.
But almost a year after the U.S. Army Corps of Engineers announced plans to fix a crumbling sea wall and fill in eroded beach areas, the restoration has yet to begin.
And now the project is trapped in the cross-currents of a more controversial project planned for nearby Nantucket Sound: Cape Wind.
State officials announced in March that Cape Wind Associates, the Boston-based company proposing 130 wind turbines in the Sound, has agreed to put up $780,000 for the Bird Island project if the wind farm is approved and becomes operational.
The payment, meant to offset concerns that the turbines could kill roseate terns and other birds, would be the final piece in the Bird Island funding puzzle.
But tern advocates fear the money may never materialize, given the history of controversy and delay surrounding Cape Wind.
And there is considerable discomfort that comes with tying the Bird Island restoration to a project that, researchers fear, could kill birds.
Ian Nisbet, a retired environmental science consultant who has studied the roseate and common terns of Bird Island for nearly 40 years, said he does not know what to make of Cape Wind.
“I think the jury is out,” he said. “It’s potentially a very serious matter for the terns.”
Cape Wind filed its environmental impact report with the state in February. The document includes bird research by Cape Wind consultants and the Massachusetts Audubon Society that found roseate terns do not frequent the proposed Cape Wind site. The report concluded that, on average, one roseate would collide with the turbines per year.
But researchers such as Taber Allison, vice president for conservation science at Massachusetts Audubon, say the report is incomplete because it only examines the terns’ daytime flight patterns.
A complete analysis, Allison said, would include a survey of flights between dusk and dawn, using transmitters attached to birds and tracked by plane or satellite.
Cape Wind Associates stands by the environmental impact report, which was approved by the state’s top environmental official in March, and argues the alternative energy project would ultimately serve the terns well.
“Global warming represents the greatest threat to birds and other wildlife, and Cape Wind is the type of response that is needed to address this urgent problem,” Mark Rodgers, a spokesman for Cape Wind Associates, said in an e-mail message.
But whatever the virtues of Cape Wind, and the pitfalls of linking the controversial project to the fate of Bird Island, researchers say a restoration of the breeding ground is crucial if the roseate tern is to thrive and the mysteries of the graceful creature are to be uncovered.
Most roseate terns nest in tropical and subtropical areas of the Indian, western Pacific and western Atlantic oceans. But temperate zone breeding populations are found in North America, Europe, Japan and South Africa.
The northeastern North American population ranges from New York to Nova Scotia, Canada. And some 90 percent of the U.S. roseate tern population, which totaled about 3,300 pairs last year, nests on just three islands: Great Gull Island off the tip of the northern fork of Long Island, Ram Island in Buzzards Bay, and nearby Bird Island.
The declining number of suitable nesting grounds – squeezed by human activity, competition from gulls and threats posed by raccoons, owls and other predators – was the chief reason the U.S. Fish and Wildlife Service declared the population endangered in 1987.
Their fragile island habitats make the wispy birds particularly susceptible to a hurricane or oil spill, say researchers.
But a local disaster, natural or otherwise, does not explain the sharp decline in the region’s roseate tern population from a peak of 4,300 pairs in 2000, according to researchers.
“It’s a mystery,” said Carolyn Mostello, a wildlife biologist for the state Division of Fisheries and Wildlife, which has run a Buzzards Bay tern restoration project since 1998.
Mostello suspects something is happening in the birds’ wintering grounds, which seem to be concentrated in Brazil and other northerly sections of South America.
To learn more, researchers are attaching monitoring devices to roseate terns this spring to record sunrise and sunset times, which can be used to track the latitude and longitude of a bird within 150 kilometers.
Biologists are also trying to divine the reason for a significant gender imbalance among the roseate tern population. About 57 percent of the birds are female and 43 percent male.
Jeffrey Spendelow, a wildlife biologist with the U.S. Geological Survey who coordinates a regional study of roseate terns, said males may be wearing themselves out providing more of the food and care for the young than females.
Whatever the reason, the imbalance has led to a number of female-female pairings, which are generally less successful than male-female pairings. The females in single-sex pairings have trouble getting males to fertilize their eggs, researchers say. And when a chick is hatched, females are reluctant to stray from the nest and forage for the fish required to keep the young alive.
Restoring Bird Island as a prime nesting ground is seen as a crucial step to reversing the decline in the roseate tern population.
Bird Island is a ragged spit of rock and sand with a modest lighthouse that dates to 1819 and, according to local legend, was once tended by a banished pirate.
The sea wall that surrounds the island is almost as old as the lighthouse and does not deflect the waves like it once did. The beach behind the wall is slipping away.
The erosion has pushed the feisty common terns at the perimeter of the island to the more protected center where they, in turn, are forcing out the roseates.
The Army Corps plan calls for fixing the wall by dredging sand from the Cape Cod Canal’s Hog Island Channel, and filling in about one-half acre of beach.
Researchers hope the project could restore a natural balance. But for now, that balance appears elusive.
And the fate of the Bird Island terns, which whir in a chirping gyre around the old lighthouse, is tied to the uncertain whir of 130 wind turbines in Nantucket Sound.
By David Scharfenberg
Cape Cod Times
27 May 2007
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