Cooperative Research Units
Education, Research And Technical Assistance For Managing Our Natural Resources
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Barred owls in the Pacific Northwest: using an experimental removal project to understand predator-prey interactions of a non-native raptor.


September 2016 - August 2021


The barred owl (Strix varia) is a medium-sized forest owl native to eastern North America (Mazur and James 2000). Starting in the late 1800’s, the barred owl began expanding its geographic range north and west, and their newly expanded range now completely overlaps that of the federally threatened northern spotted owl. Strong evidence indicates that competition with invading barred owls is causing rapid declines in populations of spotted owls, and that in some portions of the Pacific Northwest, barred owls now occur at much greater densities relative to spotted owls. However, little research exists on the overall impacts of this newly established apex predator on other forest species (besides spotted owls) and food-web dynamics. In collaboration with USGS-FRESC and USFWS, this project will take advantage of the experimental design associated with an on-going barred owl removal experiment to evaluate the impact this novel avian predator is having on the food web in the PNW. Understanding the impact of barred owls on the food web is critical for spotted owls and other native species, particularly as barred owl densities reach carrying capacity in the PNW.


Current Staff

Federal Staff: 101

Masters Students: 239

Phd Students: 154

Post Docs: 55

University Staff: 241

5 Year Summary

Students graduated: 695

Scientific Publications: 1962

Presentations: 4417



Funding Agencies



Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey