Scientists race to find out why eagles are dying

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Clues lead down food chain to coots, plants and algae

THURMOND LAKE -With a sudden flurry of flapping wings and feet tip-toeing along the water, the coots took flight in a tight formation across the lake.

Except one, which wobbled skyward, giddy in flight, and plopped down heavily in the water.

The bird paddled furiously and desperately flapped a wing. It sank and spun under the water, and sank again, its feet in the air, stroking in a crazed, drowning dance.

The biologists swept by in a boat and plucked the dazed coot from the water.

"You're having a bad day, huh?" Susan Wilde said to the dying bird. "Well," she said, "it's not going to get any better."

She handed the bird to Tom Murphy.

Murphy turned his back to the others in the boat on Thurmond Lake. With a firm push, he snapped the bird's neck.
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Since 1994, when 29 bald eagles were found dead on DeGray Lake, Arkansas, a mysterious disease has killed hundreds of birds across the Southeast.

These are just the eagles they find. How many more may be dead they don't know.

And with just 162 breeding eagle pairs in the state, every death is a serious blow to the efforts to restore America's national symbol to the wild.

"It's set back the (bald eagle) recovery on the reservoir by more than a decade," said Murphy, eagle specialist for the S.C. Department of Natural Resources.

Despite seven years of urgent and intense research, dozens of scientists across the country have yet to solve a mystery: What's driving coots crazy? What's causing bald eagles to fly into trees and rock ledges? What's killing bald eagles?

In South Carolina, biologists think they are closing in on the killer, which may lie deep and thick below the water.
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With their black bodies, white bills, red eyes, strangely bright aqua-blue legs and three-toed feet, the American coot appears to have been handed all the parts other creatures didn't want.

The hen-sized cross between bird and duck is common and doesn't get much respect, including from its predator, the bald eagles.

Murphy describes the hunt this way: An eagle swoops down on a coot, not intending to attack. Not knowing that, the coot dives underwater but can hold its breath for just a few seconds. The eagle, circling above, swoops again, and again the coot ducks underwater. The eagle keeps swooping until the coot is exhausted.

The final time, when the coot comes up gasping for air, the eagle strikes.

"Coots are like candy to them," Murphy said.

Two years after the first bald eagles were found dead on Lake DeGray, another 26 turned up dead. At the time, biologists noticed that coots on the lake were acting strange, having trouble with their balance in air and on the water.

Both eagles and coots were found to have lesions on their brains, and scientists as-sumed the bald eagles got the new disease after eating stricken coots.

This made sense since, to eagles, the defenseless coots were easy prey.

Scientists called the new disease Coot and Eagle Brain Lesion Syndrome.

When a great-horned owl also came down with the neurological disease, that too made sense, since the owls also prey upon coots.

To further support the theory, University of Georgia biologists gutted a rat and filled its insides with all the parts of a coot infected with the disease. They fed the rat to a non-releasable red-tailed hawk. In six days the hawk was dead.

The problem was, the biologists did not know how coots were getting the brain disease.

Nor could they explain its spread. In the winter of 1996, dead eagles were found at two other lakes in Arkansas. The following year, affected coots turned up at a lake near Forsyth, Ga. The same year, coots with the same lesions were found at a man-made lake at a residential development south of Raleigh, N.C.

In the winters of 1998 and 1999, coots began dying in South Carolina, at Thurmond Lake, Lake Murray near Columbia, and two lakes in the sprawling Savannah River Site, a federal nuclear weapons facility.

In 1999, other birds, including Canada geese, mallards, and widgeon and bufflehead ducks were found to have the same lesions. They don't eat coots. So how did they get the lesions?

Scientists searched for similarities in the birds' diets. They tested water quality, and plants and sediments. In one test, they directly fed coots, quail and kestrel plants and pond scum that might contain the toxin causing the lesions.

They watched the birds to see if they died. The birds didn't.

They took farm-raised geese, clipped their wings to keep them from flying away, and placed them in the same lake in North Carolina where the coots were dying. In a week, the geese were dead.

>From this study, biologists figured birds were not getting the lesions from somewhere else, then migrating to their wintering grounds. The answer was in the lakes themselves.

So they looked for similarities in the lakes. They were all man-made impoundments, all had relatively good water quality, and all had aquatic vegetation, including a non-native, invasive species called hydrilla.

Complicating the puzzle, coots, eagles and other birds were coming down with the disease only in November and December. Why?

Biologists banded and monitored coots, watching for signs that they had gone goofy -which, with coots, is not as simple as it may seem.

"They're kind of crazy. That's why it's hard to tell if they're acting crazy," Wilde said.

They watched eagles for their migrating, hunting and eating patterns and examined bird brains and livers under microscopes. They collected more plants, consulted each other, met in conferences, and asked for the public's help in spotting dying or diseased birds.

Prompted by the spread of the disease to other birds in 1999, they changed its name to Avian Vacuolar Myelinopathy, or AVM.

But they still had no idea what caused it.

"So much of science is following leads," said Kim Miller, a wildlife disease specialist at the National Wildlife Health Center in Madison, Wis.

"Sometimes leads generate more leads, and sometimes leads generate a dead end. Sometimes it's just being in the right place at the right time."
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The boat bounced across Thurmond Lake toward a patch of smooth, still water amid wind-whipped waves.

With a scratching sound, the hull slid into the weeds on the lake's surface.

Below the boat was a vast underwater forest, its branches flowing gently with the tide. This long and sinewy vine is hydrilla, and it can spread as quickly across a lake or slow moving river as kudzu over an abandoned farmhouse.

It came from Africa and appeared in South Carolina in the 1970s. Now it chokes lakes all over the Southeast and is cursed by boaters everywhere.

In the mid-1990s, hydrilla covered 45,000 acres of the 171,000 acres of lakes Moultrie and Marion north of Moncks Corner. To halt the spread, Santee Cooper, the state-owned utility that manages the lakes, imported tens of thousands of Chinese grass-eating carp with voracious appetites to chomp through the weed.

The sterile carp, which eat four times their weight daily, ate more than the lake's managers had ever imagined. In two years, the hydrilla infestation was reduced to 7,000 acres.

But every year across the state, hundreds of thousands of dollars are spent to control the weed, which grows thick in Lake Marion, Lake Murray, in the Goose Creek Reservoir near Charleston, and in the upper reaches of the Cooper River near Moncks Corner.

Wilde pulled a clump from Thurmond Lake, where hydrilla has begun to spread. Across a wide cove, coots swam in the calm water.

The federal express package arrived at Wilde's home on Daniel Island while she was away. A neighbor signed for it.

That Saturday night, last month, Wilde took the package to her lab at the state's wildlife research center on James Island.

Inside the package was a two-liter plastic container sent by a federal engineer. It contained hydrilla stalks collected at Thurmond Lake.

Wilde, an aquatic ecologist at the Marine Resources Research Institute in Charleston, placed the stalk under the microscope. When she turned the magnification up 400 times, she noticed a colony of blue-green algae attached to the stalk.

She flipped a switch for a fluorescent light on the microscope. The lens exploded in color, and suddenly she was peering at large, bright red, shining balls - blooming, and possibly toxic, algae.

"I just thought this is it. This must be it," Wilde said. "I was so excited."

The pieces fit.

"We know the algae is occurring at the time the birds are getting sick. It's abundant, and I know they (coots) are eating it," she said.

But if the algae were toxic, why had it not been exposed as the killer before? And if it was common on hydrilla, why weren't birds dying of AVM wherever hydrilla grows?

By the end of this past week, she had tentatively identified the algae, Hapalosiphon fontinalis. Wilde calls it blue-green.

"So we have a name, probably. We have a lot of it on the hydrilla the coots are eating. But we still don't know that it is toxic. They could just be eating harmless blue-greens and getting AVM from some other source," she said.

Then again: "If we knew that the hydrilla is getting the coots sick, we're really on to something here," she said. "It has the most potential of any hypothesis that we have going on."

But were the coots, in fact, eating plants infested with blue-green? And is blue-green really abundant on Thurmond Lake?

Wilde studied the clump of hydrilla in her hand. On it was black splotches, something that any gardener might spot on a typical household plant.

But massed together, the splotches form a brown scum. Wilde was sure it was blue-green.

"I know my scum," she said.
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Tom Murphy put the dead coot in a bag.

Later that afternoon last week, he clipped out the brain and prepared it for shipping to researchers at the Southeastern Co-operative Wildlife Disease Study at the University of Georgia.

Wilde got the rest of the bird.

Later that night, she spooned out sand from the coot's gut. Through the microscope, she clearly saw blue-green in the stomach.

"Just another little piece of the puzzle," she said.

Fearing that more bald eagles will die as each day passes, biologists are racing to connect the pieces. But even as they do, others appear.

Murphy, for instance, said wildlife officers have noticed fewer muskrats at Lake Murray. Could they be getting AVM after eating hydrilla along the shore? Or maybe there are fewer muskrats simply because of the state's long drought. Biologists are still on the hunt for a muskrat to test the theory, he said.

Results are pending, meanwhile, on whether blue-green is toxic.

And this week, Wilde will be motoring across the Santee Cooper lakes and along the upper reaches of the Cooper River, searching for brown scum and crazy coots.
       by   Arlie Porter     Charleston Post and Courier

In your time spent on and near the water while boating, should you notice any coots acting strange, or worse, notice a dead or obiviously ill Eagle or Osprey then contact your LOCAL WILDLIFE MANAGEMENT AGENCY or nearby University Biology Department.