Sea Birds Face Eviction
by Beth Casper
Researchers will study the migration patterns
of Caspian terns, which eat juvenile salmon
David Craig separated the feathers of a 2-year-old Caspian tern to study its specially fitted neoprene harness.
The gull-like bird screamed and tried to peck at Craig’s arms.
“Hey now,” the Willamette University researcher said.
The harness, tight against the bird’s body, holds a transmitter that will help researchers study the birds’ migration.
Almost 10,000 Caspian terns — considered the largest colony in the world — return to East Sand Island in the mouth of the Columbia River every year after spending the winter in Mexico.
But no one knows exactly how they get from place to place — apart from the fact that they fly — and what they do throughout the winter.
The research will add to the growing body of knowledge about the controversial Caspian tern. However, it will be too late to influence a decision about where the birds should nest in the summer.
Federal agencies have proposed permanently moving the colony off East Sand Island to as far away as San Francisco Bay to protect endangered juvenile salmon from the beaks of the sea birds.
Federal managers say the move would protect the birds as well as salmon, as a disease or oil spill could wipe out the bird colony in one season. But bird advocates are screaming like gulls about the draft plan, and even some fish advocates say the Caspian tern is unfairly blamed for a problem created by humans.
In 1996, researchers discovered that each year, Caspian terns on Rice Island in the Columbia River were eating 10 million to 12 million juvenile salmon migrating out to sea.
Federal researchers estimated that terns were picking off almost 10 percent of the endangered fish.
“This was not just a drop in the bucket,” said Dan Roby, Oregon State University professor and Caspian-tern researcher. “That’s more than one dam destroys during out-migration (of salmon). One dam kills about 3 percent of salmon if no water goes over the dam. And these fish are on the verge of going out to the ocean, where presumably survival will be better.”
Most of the Rice Island colony was moved to East Sand Island by 2001, with the help of love-bird music and decoys to attract them 16 miles downriver and vegetation planted to keep the terns off the Rice Island turf.
Federal officials hoped — and got their wish — that terns on the new site would feast on delicacies such as herring and anchovies instead of salmon.
In 2003, Caspian terns on East Sand Island ate 4 million salmon — one-third less than the amount they ate on Rice Island, Roby said.
But for federal managers responsible for restoring dwindling salmon populations, the birds’ dinner too often still is salmon.
“It’s quite clear that there are enormous numbers of Caspian terns in the lower Columbia, and they eat enormous numbers of juvenile salmon on their way into the ocean,” said Brian Gorman of the National Marine Fisheries Service, which is responsible for protecting the endangered salmon. “It’s not a matter of blaming the birds for doing what nature tells them to. It’s a matter of trying — in as gentle a way as possible — to discourage the birds from nesting where they are.”
Bird advocates agree that a huge population of Caspian terns in one area is dangerous for the birds — an oil spill or bird disease could wipe out the birds.
But they disagree that the birds should be moved — and moved far — to save salmon.
“They are scapegoating these birds,” said Alex Morgan, conservation-program director for the Seattle Audubon Society. “There is no science to show that these birds are as significant a cause of decline as harvest, hydropower, habitat loss and hatcheries. … These birds — Caspian terns, mergansers and gulls — have all been a part of the Columbia River system for thousands of years, and to now say they are the underlying cause for salmon decline is pretty absurd.”
Even some of the salmon advocates aren’t ready to move birds to save fish.
“The Caspian-tern issue is just at the edges of salmon recovery,” said Erin Barnes of Save Our Salmon, a nonprofit in Portland. “To get to the real heart of the issue, we need to address what the majority of scientists in the Northwest have said, which is that the removal of the Lower Snake River dams is necessary for strong salmon recovery to an abundant, self-sustaining harvestable population. Although there is a problem with Caspian tern predation, the real issue is how the river is being managed and how it is flowing in that area.”
Craig’s research about the migration routes of the birds could help the U.S. Fish and Wildlife Service determine where best to move the birds.
But the results won’t come soon enough.
Craig still is working on fitting the harness perfectly to the tern — a bad fit could mean not only the loss of a $3,500 transmitter but also the death of a Caspian tern.
Craig is practicing on two terns that are being rehabilitated at the Wildlife Rehab Center of the North Coast.
He said it’s the perfect opportunity to make sure that the terns don’t catch their beaks in the harnesses while preening.
But his research won’t start until the birds are fitted with harnesses in spring and tracked during migration, which will be after federal officials decide whether to move the birds.
“That’s the reality of research and policy,” Craig said. “It would be nice if policy could always follow good science.”
And for someone who works around nesting, preening and flying Caspian terns, Craig thinks that the birds should be cherished, not despised.
“There’s lots and lots of predators of salmon, but terns get attention because they hold them in their beaks and you can see the fish,” Craig said.
“Dams, habitat destruction and pollution — the human perception is that it is a lot harder to solve or it’s very expensive, so it is exciting when there is a predator to blame. It’s an oversimplification of the problem to point fingers just at terns.”
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