LOS ANGELES, July 3 (Xinhua) -- The U.S. Fish and Wildlife Service on Wednesday released a control program to kill nearly half a million invasive barred owls in the Pacific Northwest to prevent at-risk native spotted owls from extinction.
According to the service's final environmental impact statement analyzing proposed barred owl management alternatives to protect northern and California spotted owls in Washington, Oregon and California from invasive barred owls, the implementation of the program would result in the annual removal of less than one-half of 1 percent of the current North American barred owl population.
The service said it estimates a maximum of about 450,000 invasive barred owls, or about 15,000 per year, could be removed over 30 years under full implementation of the preferred alternative.
Northern spotted owl populations are rapidly declining due to competition with invasive barred owls and habitat loss. California spotted owls face a similar risk as barred owl populations continue to move south into their range, said the service in a press release.
Barred owls are larger, more aggressive, and more adaptable than northern spotted owls. They displace spotted owls, disrupt their nesting, and compete with them for food, according to the service.
Barred owls are native to eastern North America but started moving west of the Mississippi River at the beginning of the 20th century. This expansion was likely due to human-induced changes in the Great Plains and northern boreal forest, said the service, adding that as a result, barred owls now surpass northern spotted owls in numbers across most of California, Oregon, and Washington.
Researchers have shown strong evidence that spotted owl population declines are more pronounced in areas where barred owls have moved into the spotted owl's range and are greatest where barred owls have been present the longest. Researchers have seen a few instances of barred owls interbreeding with or killing spotted owls.
"Barred owl management is not about one owl versus another," said Service Oregon Office state supervisor Kessina Lee in the press release, noting that "Without actively managing barred owls, northern spotted owls will likely go extinct in all or the majority of their range, despite decades of collaborative conservation efforts."
