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Effects of experimental removal of barred owls on population demography of northern spotted owls in Washington and Oregon—2016 progress report

April 13, 2017

Evidence indicates that competition with invasive barred owls (Strix varia) is causing rapid declines in populations of northern spotted owls (S. occidentalis caurina), and that the long-term persistence of spotted owls may be in question without additional management intervention. A pilot study in California showed that removal of barred owls in combination with habitat conservation may be able to slow or even reverse population declines of spotted owls at local scales, but it remains unknown whether similar results can be obtained in areas with different forest conditions and a greater density of barred owls. In 2015, we implemented a before-after-control-impact (BACI) experimental design on three study areas in Oregon and Washington with at least 20 years of pre-treatment demographic data on spotted owls to determine if removal of barred owls can improve localized population trends of spotted owls. Here, we report on research accomplishments and preliminary results from the first 21 months (March 2015–December 2016) of the planned 5-year experiment.

Publication Year 2017
Title Effects of experimental removal of barred owls on population demography of northern spotted owls in Washington and Oregon—2016 progress report
DOI 10.3133/ofr20171040
Authors J. David Wiens, Katie M. Dugger, Krista E. Lewicki, David C. Simon
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2017-1040
Index ID ofr20171040
Record Source USGS Publications Warehouse
USGS Organization Forest and Rangeland Ecosystem Science Center
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