By Isabelle Groc
EAST SAND ISLAND, Oregon—Alexa Piggott is crawling through a dark, dusty, narrow tunnel on this 62-acre island at the mouth of the Columbia River. On the ground above her head sit thousands of seabirds. Piggott, a crew leader with Bird Research Northwest, is headed for an observation blind from which she'll be able to count them.
It's September, and the low-lying island is relatively quiet. Most of the fledglings and their parents have left, and only a few thousand pelicans and cormorants remain. But in the spring, 60,000 birds come here to nest. East Sand Island is home to the largest breeding colony of Caspian terns in the world and the largest colony of double-crested cormorants in North America—nearly 15,000 pairs.
That's too many cormorants, says the U.S. government. Starting next spring, it proposes to shoot more than half of the iridescent black birds, on the grounds that they're eating too many fish.
The cormorants eat mostly anchovies—but they also dispatch as many as 20 million salmon and steelhead trout smolts every year. The nesting season of double-crested cormorants on East Sand happens to overlap with the migration of the juvenile fish down the Columbia to the Pacific.
"They're eating over 6 percent of all the wild steelhead that are passing through the lower Columbia River," says Ritchie Graves, a fisheries biologist with the National Oceanic and Atmospheric Administration. They also consume more than 2 percent of the yearling chinook salmon.
Besides being commercially valuable, both fish are on the Endangered Species List, and that's what's forcing the U.S. Army Corps of Engineers to act. The corps owns and manages East Sand Island; indeed, it created the bird colony when it expanded the island with dredging spoils back in the 1980s.
Last summer the corps announced a proposal to kill 16,000 double-crested cormorants on the island over a period of four years. It also proposes to remove enough sand to inundate the nesting area of the cormorants, so that birds that leave won't come back. The goal is to reduce the double-crested cormorant population on East Sand Island to about 5,600 breeding pairs.
The move is part of a growing trend toward what wildlife managers sometimes call "lethal control"—killing one species of animal to protect another.
Lethal control of natural predators "is slowly becoming a dominant conservation strategy," says Michael Nelson, a professor of environmental ethics and philosophy at Oregon State University, in Corvallis. "We are embracing this as the first line of defense."
As the strategy is playing out at local levels, it is drawing opponents. That includes Piggott, who is dismayed by the corps' plan to shoot cormorants.
"We have built a level of trust between the researchers and the birds that nest around the blinds," she says. "It makes me sad and angry that we are breaking this relationship and using the blinds against the birds. They have no idea what's coming."
Picking Species to Save
For most wildlife managers, lethal control is probably an uncomfortable choice, but it's one they're finding themselves forced into more often these days—forced by humanity's expanding impact on nature to meddle with it some more. "With society having a bigger and bigger footprint, [the practice of lethal control] can only increase," says Michael Scott, an ecologist at the University of Idaho, in Moscow.
Climate change, which causes animals to move into new ranges and interfere with one another in new ways, can only exacerbate the dilemma, says Bob Sallinger, conservation director of the Audubon Society of Portland. "How much manipulation of these species do we want to do to protect one from another?" Sallinger asks.
We already do quite a lot. Starting in the 1970s, thousands of brown-headed cowbirds were killed in Michigan to keep them from invading the nests of endangered Kirtland's warblers. Last year the U.S. Fish and Wildlife Service began killing up to 3,600 barred owls in Washington, Oregon, and northern California to save northern spotted owls. More....