Effects of experimental removal of Barred Owls on population demography of Northern Spotted Owls in Washington and Oregon—2017 progress report
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Abstract
Populations of Northern Spotted Owls (Strix occidentalis caurina; hereinafter referred to as Spotted Owl) are declining throughout this subspecies’ geographic range. Evidence indicates that competition with invading populations of Barred Owls (S. varia) has contributed significantly to those declines. A pilot study in California showed that localized removal of Barred Owls coupled with conservation of suitable forest conditions can slow or even reverse population declines of Spotted Owls. It remains unknown, however, whether similar results can be obtained in areas with different forest conditions, greater densities of Barred Owls, and fewer remaining Spotted Owls. During 2015–17, 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. Each study area had at least 20 years of pre-treatment demographic data on Spotted Owls, and represented different forest conditions occupied by the two owl species in the Pacific Northwest. This report describes research accomplishments and preliminary results from the first 2.5 years (March 2015–August 2017) of the planned 5-year experiment.
Suggested Citation
Wiens, J.D., Dugger, K.M., Lesmeister, D.B., Dilione, K.E., and Simon, D.C., 2018, Effects of experimental removal of Barred Owls on population demography of Northern Spotted Owls in Washington and Oregon—2017 progress report: U.S. Geological Survey Open-File Report 2018–1086, 23 p., https://doi.org/10.3133/ofr20181086.
ISSN: 2331-1258 (online)
Study Area
Table of Contents
- Abstract
- Background and Study Objectives
- Experimental Study Areas
- Methods
- Preliminary Results, March 2015–September 2017
- Associated Research Activities and Accomplishments
- Summary
- Work and Reporting Schedule
- Acknowledgments
- References Cited
- Appendixes 1–2
Publication type | Report |
---|---|
Publication Subtype | USGS Numbered Series |
Title | Effects of experimental removal of Barred Owls on population demography of Northern Spotted Owls in Washington and Oregon—2017 progress report |
Series title | Open-File Report |
Series number | 2018-1086 |
DOI | 10.3133/ofr20181086 |
Year Published | 2018 |
Language | English |
Publisher | U.S. Geological Survey |
Publisher location | Reston, VA |
Contributing office(s) | Forest and Rangeland Ecosystem Science Center |
Description | iv, 23 p. |
Country | United States |
State | Oregon, Washington |
Online Only (Y/N) | Y |
Google Analytic Metrics | Metrics page |