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Ecology and salmon related articles

Tern Relocation Turns Out Popular

by Jonathan Brinckman
The Oregonian, May 16, 2002

Biologists say the program is a temporary measure
to help restore the natural populations of fish

Who says you can't tell a tern what to do?

The thousands of Caspian terns jamming Rice Island and gobbling up millions of baby salmon from the Columbia River have heeded a directive from the U.S. government: move downriver, to the mouth where anchovies make a perfectly good lunch, and park it on East Sand Island.

The birds did it. Over the past six weeks more than 13,000 of them arrived from Mexico and, as if guided by aavian air traffic controller, set down on a sandy patch of East Sand Island, right by the Pacific Ocean.

It hasn't been easy -- or cheap.

Six years ago the U.S. Army Corps of Engineers started looking into whether it could relocate the colony, thought to be the largest in the world. Dan Roby, of Oregon State University, told the federal agency it might be possible.

But several tricks -- bird annoyances on Rice Island, bird enticements on East Sand Island -- would be involved: On Rice Island, plant grasses that interfere with nesting. Terns lay eggs in depressions they scrape in the sand. This helps them spy approaching predators. Also build wood-slat fences that impede sightlines, spooking the terns into "worrying" about predators on the other side. On East Sand Island, clear out vegetation to create open sandy beach. Set up tern decoys to make the place look popular and draw more terns, just as a crowded restaurant draws more people. Turn up the stereo -- in this case, loud recordings of a happy tern colony. And for real juice, post two armed (and real) humans to keep the gulls away from tern nests.

It worked. Terns began moving to East Sand Island, about 20 miles west.

But just as quickly, everything went sour -- that is, if you feel the terns were showed no disrespect in the relocation.

The National Audubon Society and three other groups sued the corps and the U.S. Fish and Wildlife Service on behalf of the terns, saying the United States was harassing the birds in violation of the Migratory Bird Act. A federal judge in Seattle first issued a temporary restraining order in April 2000 forbidding any harassment of terns. She then issued a permanent injunction in August 2001 prohibiting both tern harassment and efforts to make East Sand Island tern-friendly.

But the terns don't follow court decisions. They weren't about to reverse their new behavior: Because the corps had already planted grasses on Rice Island and cleared a patch on East Sand Island, they continued their relocation.

Even so, the government's stick-and-carrot effort must be continuous to ensure that the terns wouldn't decide -- if anything, they show independence of mind -- that Rice was better, after all, and undo everything.

With a legal settlement of the case in early April -- just before the anticipated annual arrival of the terns -- the corps set about clearing 6.5 acres on East Sand Island.

It's as if the birds liked the bulldozer. Unfazed by the engine's roar, they landed and set up birthing grounds. Thirteen thousand strong.

Yesterday, officials report, nary a single Caspian tern was roaming about Rice Island, where salmon fingerlings and young adults gather before striking out into the ocean.

"It feels great," Roby said Wednesday. "I think we've finally done it."

The tab? The corps has spent about $100,000 since 1999, mostly on removing vegetation from East Sand Island. An ongoing research and monitoring effort on the effects of bird predation on salmon, which includes the Caspian tern colonies, has cost more than $2 million since 1997.

But there is a salmon savings. The terns had picked off about 12 million salmon from their perch on Rice Island. Now, on East Sand Island, that number is cut in half and "subsidized" by voluminous anchovy populations.

"In terms of saving salmon, this is by far the most cost-effective program out there," said Bob Willis, chief of environmental resources for the Portland District of the corps.

For all the success, however, Roby isn't completely satisfied. He cites the need to find other nesting sites for the terns, so they won't be wiped out by a single catastrophe such as a disease outbreak or a flood.

"I won't feel closure until we have restored Caspian terns elsewhere in the Northwest," Roby said Wednesday. "That colony contains two-thirds of the Pacific Coast population of Caspian terns."

Related Pages:
Columbia Bird Research

Jonathan Brinckman
Tern Relocation Turns Out Popular
The Oregonian, May 16, 2002

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