Wiens, J.D., K.M. Dugger, D.B. Lesmeister, K.E. Dilione, and D.C. Simon. 2019. Effects of Barred Owl (Strix varia) removal on population demography of Northern Spotted Owls in Washington and Oregon, 2015-18. U.S. Geological Survey Open File Report 2019-1074, 17pp. hppts://doi.org./10.3133/ofr20191074.
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