Artificial Islands Wean Terns
by Jeff Barnard
ADEL, Ore. - Biologists had no sooner set out a couple hundred plastic Caspian tern decoys and turned on a recording of the birds squawking than five real ones flying overhead came around for a closer look.
In a matter of months, some 800 Caspian terns were sitting on eggs, feeding small fish to chicks, fending off marauding gulls and doing what their ancestors did before a tiny island in a desert lake here was destroyed in the 1950s by people looking for arrowheads with a bulldozer.
This rock and sand reinvention of nature was never about the terns, however. They are not protected by the Endangered Species Act. It was about making them less of a monkeywrench in the untold billions of dollars spent on restoring salmon threatened with extinction by hydroelectric dams and other factors hundreds of miles away at the mouth of the Columbia River.
The official name for the project is Columbia River Avian Predation Project.
"If it were up to the U.S. Fish and Wildlife Service, as much as they might want to build these islands, there is no way they could afford to," said Dan Roby, a professor of wildlife ecology at Oregon State University who is watching over the tern relocation project. "The resources are only there because it makes sense in the context of the major effort to try to restore salmonids in the Columbia Basin."
With tern nesting islands in short supply around the West from a century of human development, some 14,000 of the birds crowd onto a little island at the mouth of the Columbia River each summer, where they pig out on 5 million baby salmon a year. That amounts to about 5 percent of the total coming down the Columbia to the Pacific, some of which are on the threatened and endangered species lists.
With so many terns nesting in one spot, conservation groups were worried they could be wiped out by some catastrophic event, and sued the Army Corps of Engineers, which operates the dams, to come up with a solution. The corps agreed to go into the habitat restoration business, budgeting $2.7 million to build new nesting islands farther away and persuade the terns to move there.
This one in Crump Lake was finished in March in true Army Corps of Engineers style, armored with rock so it would never wash away. More islands will follow this year and next year on traditional tern migration routes in Oregon, Northern California and San Francisco Bay.
Kieran Suckling is happy to see things turning around, no matter what the reason. Suckling, policy director at the Tucson, Ariz.-based Center for Biological Diversity, has fought to protect dwindling habitat for frogs, salmon, sage grouse and spotted owls.
"Habitat restoration is the single best and usually cheapest thing we can do to restore imperiled species," he said. "And more often than not we have been destroying habitat or seeking expensive technological fixes when the simple low-tech project of restoring habitat is the best thing we should do. It's what we should be doing everywhere all the time."
Desperate for islands that offer a water barrier to predators like foxes, as well as bare sandy ground in which to lay their eggs, Caspian terns had first colonized Rice Island, 15 miles upstream from the mouth of the Columbia. The island was a dumping ground for the sand dredged out of shipping channels.
When biologists figured out the terns were eating too many young salmon migrating to the ocean, they drove them off Rice Island and lured them to East Sand Island, closer to the ocean, where other fish became part of the tern diet. But the 14,000 birds there, representing 70 percent of the birds in the Western U.S., still ate too much.
The first new tern island, on Fern Ridge Reservoir in the Willamette Valley near Eugene, has done poorly - a video monitor spotted only a couple birds this year. Besides being off the historical migration paths of Caspian terns, it is on a lake busy with people, Roby said. The second was this one on Crump Lake, located a few miles outside the desert outpost of Adel, which has far exceeded expectations.
More islands are planned for nearby Summer Lake, in Tule Lake and the Lower Klamath National Wildlife Refuge in Northern California, and in San Francisco Bay.
As new nesting islands are built, the Corps will allow the weeds to grow back on East Sand Island, squeezing the terns out.
The cost of building the remaining islands is likely to take the project over the original $2.7 million budget, especially in San Francisco Bay where materials are expensive, said Army Corps of Engineers biologist Geoff Dorsey, who is in charge of the project. The later ones will depend on future funding being approved by Congress.
The San Francisco Bay islands are planned for Don Edwards San Francisco Bay National Wildlife Refuge and the Hayward Regional Shoreline.
Crump Lake Island, which cost $800,000, gives the birds a place to themselves, except for biologists Frank Mayer and Megan Jones, who did daily counts of terns and their chicks, documented what kinds of fish they ate, and interactions with gulls that also nested on the island, throughout the summer nesting season.
And the 400 or so nests Mayer and Jones have counted far exceed the goal of just 71 the first year. They also spotted terns carrying leg bands showing they were born on East Sand Island and Rice Island in the Columbia, as well as a couple nesting sites in Washington, and one bird born at Crump Lake five years ago.
Roby said a key to the success at Crump Lake is terns had nested here before. Though Caspian terns live to be 30 years old, none is old enough to remember the island before it fell to the artifact hunters' bulldozer. But some die-hard birds never gave up on their birthplace.
In 2003, Roby and a crew were studying food sources at Crump Lake when some terns were flooded out of their nests by rising water. The biologists built a plywood platform above the rising waters, threw sand on it, and the terns - desperate for habitat - resumed nesting.
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