Improving strategies to assess competitive effects of barred owls on northern spotted owls in the Pacific Northwest

http://pubs.usgs.gov/fs/2011/3096/

A scientific study has determined that survey methods designed for spotted owls do not always detect barred owls that are actually present in spotted owl habitat.

by Wiens, J. David and Weekes, Anne

U.S. Geological Survey Fact Sheet 2011-3096

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