SAN FRANCISCO (AP) – A biologist and contractor with a lumber company is at the heart of an experiment sanctioned by the U.S. Fish and Wildlife Service: killing bully owls to protect endangered owls.

The San Jose Mercury News reports biologist Lowell Diller kills barred owls, which are known to bully the smaller northern spotted owl.

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The spotted owl, a Pacific Northwest native, is threatened with extinction and has become the symbol of the region’s timber conservation battles.

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Diller, a contractor for Green Diamond Resource Co., a lumber company managing timberland in Humboldt, Del Norte and Trinity counties, says the barred owl is an amazing bird. But it has invaded California from the eastern United States, muscling out northern spotted owls upstate, and spreading south toward San Francisco.

A study soon to be published in the Journal of Wildlife Management and Wildlife Monographs shows Diller’s grisly conservation experiment works.

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Copyright 2016 The Associated Press.