When a Once-Endangered Species Becomes a Threat

In 2007, the bald eagle was officially (and with plenty of pomp and circumstance) removed from the endangered species list. Now, High Country News reports, conservationists face a difficult question: What to do about the fact that these eagles are wreaking havoc on seabird populations along the coasts of Oregon and Washington?

The Oregon coast now supports over a million nesting seabirds, including common murres, storm petrels, western gulls, cormorants, and tufted puffins. While none are federally endangered, Washington regards common murres and tufted puffins as species of concern (along with bald eagles); the puffins are also considered “sensitive” in Oregon. After the bald eagle’s decline, these seabirds nested for generations without being harassed, says Isaacs: “I feel sorry for the seabirds.” These days, on the northern part of the coast, bald eagle predation has caused the collapse of entire murre colonies, once 300,000 birds strong. “Some of our rocks that were significant colony sites are now permanently abandoned,” Lowe says.

For now, scientists seem to be watching and waiting. Not much is known about the bald eagle’s historical population levels and interactions with murres and gulls–these “raids” on seabird colonies, High Country News notes, “may simply represent a shift towards balance.”

Researchers speculate that seabirds like murres were sometimes prey for eagles in the past, and could not breed in large colonies with such a predator in the picture. The eagles might also help bring gull numbers back down to historic levels. But for less robust species, such as cormorants and great blue herons, the raptor’s indiscriminate appetite could prove a problem.

Historically, bald eagles fed opportunistically on a wide variety of prey, including salmon and mammals, but decades of decline in wild salmon populations may have forced them to dine on other birds more frequently. “Predator-prey relationships are not a new threat,” says Steve Mashuda, an attorney with the nonprofit environmental law firm Earthjustice. “It is only a threat in the context of an imbalance that is largely human-caused.” Many seabird populations are already impaired because of human activities, including oil spills, fishery by-catch, and loss of habitat to development.

Source: High Country News

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