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Effects of experimental removal of Barred Owls on population Demography of Northern Spotted Owls in Washington and Oregon—2018 Progress Report

June 28, 2019

Populations of Northern Spotted Owls (Strix occidentalis caurina; herineafter referred to as Spotted Owl) have declined throughout the subspecies’ geographic range. Evidence indicates that competition with invading Barred Owls (S. varia) has contributed significantly to those declines. A pilot study in California showed that removal of Barred Owls coupled with conservation of suitable habitat conditions can slow or even reverse population declines of Spotted Owls. It is unknown, however, whether similar results can be obtained in areas with different forest conditions, greater densities of Barred Owls, and fewer remaining Spotted Owls. We initiated a before-after-control-impact (BACI) experiment at three study areas in Oregon and Washington to determine if removal of Barred Owls can improve population trends of Spotted Owls. This report describes research accomplishments and initial results from the first 3.5 years of the study (March 2015–August 2018).

Citation Information

Publication Year 2019
Title Effects of experimental removal of Barred Owls on population Demography of Northern Spotted Owls in Washington and Oregon—2018 Progress Report
DOI 10.3133/ofr20191074
Authors J. David Wiens, Katie M. Dugger, Damon B. Lesmeister, Krista E. Dilione, David C. Simon
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2019-1074
Index ID ofr20191074
Record Source USGS Publications Warehouse
USGS Organization Forest and Rangeland Ecosystem Science Center

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