This dataset includes anticoagulant rodenticide (AR) screening results of 40 Barred Owls (Strix varia) collected in forested landscapes of Washington and Oregon from 2015-2017. Liver tissue was collected from each owl and screened for exposure to eight AR compounds, including 4 first-generation ARs (warfarin, diphacinone, chlorophacinone, and coumachlor), and 4 second-generation ARs (brodifacoum, bromadionlone, difethialone, and difenacoum). Additionally, this dataset includes geographic, temporal, environmental, and biological attributes of individual owls that were identified as potential sources of variation in AR exposure and/or useful measurements for assessing AR exposure risk of sympatric northern spotted owls (S. occidentalis caurina). Lethal removal and scientific collection of barred owls was approved by the Institutional Animal Care and Use Committee at Oregon State University (Protocols 4728, 5067), and completed under Federal Fish and Wildlife Permit MB14305B-0 and Washington (HENSON 18-261) and Oregon (MB14305B-5) State Scientific Collection Permits.