Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Anticoagulant rodenticides in Strix owls indicate widespread exposure in west coast forests

    Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): J. David Wiens; Krista E. Dilione; Collin A. Eagles-Smith; Garth Herring; Damon B. Lesmeister; Mourad W. Gabriel; Greta M. Wengert; David C. Simon
    Date: 2019
    Source: Biological Conservation. 238: 108238-.
    Publication Series: Scientific Journal (JRNL)
    Station: Pacific Northwest Research Station
    DOI: https://doi.org/10.1016/j.biocon.2019.108238
    PDF: Download Publication  (1.0 MB)

    Description

    Exposure of nontarget wildlife to anticoagulant rodenticides (AR) is a global conservation concern typically centered around urban or agricultural areas. Recently, however, the illegal use of ARs in remote forests of California, USA, has exposed sensitive predators, including the federally threatened northern spotted owl (Strix occidentalis caurina). We used congeneric barred owls (S. varia) as a sentinel species to investigate whether ARs pose a threat to spotted owls and other old-forest wildlife in northern regions of the Pacific Northwest. We analyzed the liver tissue from 40 barred owls collected in Oregon and Washington and confirmed exposure to ≥1 AR compounds in 48% of the owls examined. Brodifacoum, an extremely toxic second-generation AR, was the most common compound detected (89% of positive cases), followed by bromadiolone (11%), difethialone (11%), and warfarin (5%). Brodifacoum was also detected in one barred owl and one spotted owl opportunistically found dead (liver concentrations were 0.091 and 0.049 μg/g, respectively). We found no evidence that exposure varied with proximity to developed and agricultural areas, or among different study areas, age-classes, and sexes. Rather, exposure was ubiquitous, and the rates we observed in our study (38–64%) were similar to or greater than that reported previously for barred owls in California (40%). Together these studies indicate widespread contamination in forested landscapes used by spotted owls and other wildlife of conservation concern. Owls collected in older forests may have been exposed via illegal use of ARs, highlighting a mounting challenge for land managers and policy makers.

    Publication Notes

    • Visit PNW's Publication Request Page to request a hard copy of this publication.
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

    Citation

    Wiens, J. David; Dilione, Krista E.; Eagles-Smith, Collin A.; Herring, Garth; Lesmeister, Damon B.; Gabriel, Mourad W.; Wengert, Greta M.; Simon, David C. 2019. Anticoagulant rodenticides in Strix owls indicate widespread exposure in west coast forests. Biological Conservation. 238: 108238-. https://doi.org/10.1016/j.biocon.2019.108238.

    Cited

    Google Scholar

    Keywords

    Anticoagulant rodenticide, barred owl, brodifacoum, northern spotted owl, Strix varia, Strix occidentalis caurina.

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page
https://www.fs.usda.gov/treesearch/pubs/59298