Osprey Reputation For Fidelity Takes A Sudden Dive

Scientists Find Birdswintering Apart In Southwestern Brazil

April 24, 1997|By NEW YORK NEWS SERVICE

SHELTER ISLAND, N.Y. - Ruby-throated hummingbirds, red-wing blackbirds and great blue herons inhabit the salt marshes, freshwater ponds and pine swamps that make this storied island one of the last nature refuges of Long Island.

But it is the osprey, a fish-eating hawk that builds skyscraper nests out of junk, that has captured the imagination of generations of East Enders. Residents around Peconic Bay baby the big birds, building platforms in yards for the ospreys to nest. Tourists come to see them take their dramatic dives into the water to snap up flounder with their claws.

"New York has its World Trade Center, Paris has its Eiffel Tower and Shelter Island has its ospreys coming back every spring," said Clifford P. Clark, owner of Shelter Island's south ferry.

That sort of devotion is rooted in many things, including the almost mythical loyalty of osprey mates as they return to the same nest year after year, sometimes for a decade or more.

In an animal kingdom where polygamy and incest are the rule, the osprey has long been viewed as a paragon of virtue along with the monogamous goose and swan.

Rewriting the book

But a study being conducted here is beginning to rewrite the book on the bird, and it is putting the osprey's formerly spotless reputation in jeopardy. It is beginning to look as if ospreys are not necessarily loyal to their mates. It is their nests of twigs mixed with fish netting, cow dung and seaweed that somehow merit their attachment, if not their affection, according to the latest findings of the researchers.

The University of Minnesota's Raptor Center launched the study in 1995, using satellite telemetry to track dozens of ospreys migrating from breeding areas in Oregon, Minnesota and Shelter Island all the way to their winter hideaways as far south as Pantanal National Park in southwestern Brazil.

Outfitted with wired backpacks that emit signals for tracking by a satellite ground station in Landover, Md., the ospreys are giving scientists precise information on where they and other birds fly, and how much time they spend from place to place along their migration route.

The Nature Conservancy, a private environmental group, will supply Latin American governments with the new information as well as assistance to protect the areas where the ospreys go.

The scientists plan to work for several more years before publishing a definitive paper, but have already found that parts of Cuba and Haiti are important stopover points that require protection.

Species in good shape

The study has also found that as a species, the osprey is generally in excellent shape 25 years after it was endangered in New York state because of exposure to DDT.

But in one disturbing new finding, scientists are finding low reproduction rates along one area on the Columbia River in Oregon. And closer to home, they are finding that the ospreys have been slow to return to the 2,000-acre Mashomack Preserve on Shelter Island this year.

These could be telltale signs of environmental trouble.

So much for the pure science. Now to the details that are making the scientists clear their throats, blush and sometimes ask inquiring reporters to go off the record.

"Maybe I shouldn't say this, and I'm not ready to make any leaping statements yet," said Mark Martell, conservation coordinator at the University of Minnesota Raptor Center. "But what we're seeing is that the males and females are not wintering together. It's not very romantic."

Martell was quick to note that the study has confirmed that the ospreys do not find mates away from their North American nests. But researchers are finding that the males generally return to their breeding grounds several weeks sooner than the females they mated with the spring before.

But scientific studies don't worry students in the Shelter Island School. They have named the three most recently tagged Shelter Island birds, who are called X-4, X-5 and X-7, Kid, Chestnut and Fisher.

X-4, a female who spent her winter in Venezuela, appeared to be happy and healthy, getting ready to lay eggs at her nest above a cobble beach just west of Shelter Island's south ferry station. Her mate perched on a dead oak nearby and from time to time flew around the nest with a catch of herring, which he brought her.

'Trying to impress her'

"He's trying to impress her to show what a great fisherman he is, to show he'll be a good provider," said Michael S. Scheibel, a biologist at the Mashomack Preserve, who was making notes for the University of Minnesota study.

"There is a certain amount of pair-bonding that he has to continue to work on. Don't we all?" he added.

Next, Scheibel drove his four-wheel-drive vehicle through the preserve to Major's Point, a secluded spot far from the island's golf courses and manicured lawns, in search of X-5, another female. X-5 wintered in Brazil, and last sent a reliable satellite signal March 22 from Richmond, Va.

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