As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Friday, 15 February 2019

A Federal Bird Kill in the Columbia River Did Nothing to Save Salmon

Published February 6 at 5:31 AM  Updated February 6 at 10:09 AM
The federal government killed thousands of double-crested cormorants living on a Columbia River island between 2015 and 2017 in an effort to help young salmon make it to the Pacific Ocean alive. But Oregon state biologists say the birds just moved upriver—possibly tripling the number of salmon each bird ate.
The U.S. Army Corps of Engineers killed 5,576 cormorants and destroyed 6,181 nests in an effort to prevent the birds from eating an estimated 12 million young salmon each year as they swim past East Sand Island, just east of the mouth of the Columbia as it flows into the Pacific.
Biologists say the mass slaughter may have caused the collapse of the birds' largest breeding colony. It also may have been for nothing.
James Lawonn, biologist in charge of avian predation for the Oregon Department of Fish & Wildlife, is preparing a new study on the effects of the birds' redistribution along the river. (His study was first reported by Courthouse News Service.) Lawonn says his agency "expects little to no gain in survival" from the corps' actions for young salmon swimming through the Columbia River estuary.
That's because cormorants are now living farther upriver—still in huge numbers. And where they live makes a difference. Cormorants that live closer to the ocean choose from an extensive menu of ocean fish that form huge schools in the Columbia estuary, like anchovies, herring and smelt. Upriver, they eat a far higher proportion of salmon and other freshwater fish.
In 2017, during the bird kill, most of the colony on East Sand Island fled, in an event the Audubon Society called a "catastrophic collapse" of the largest population of double-crested cormorants in the world. The corps says there's no direct evidence to link the two events. But the mass exodus came during the corps' third year of shooting thousands of birds out of the air, destroying their nests and setting off explosives on the island.

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