Graduation Date

Spring 2022

Document Type



Master of Science degree with a major in Natural Resources, option Wildlife

Committee Chair Name

Matthew Johnson

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Daniel Barton

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Barbara Clucas


Barn owls, Biological control, Ecosystem services, Gophers, Integrated pest management, Pest control, Rodents, Tyto furcata, Vineyard, Wine

Subject Categories



Attracting natural enemies to farms to reduce pests has long been a part of integrated pest management for insects, but knowledge of the impact of raptors on rodents and other vertebrate pests is comparatively sparse. In this study, I compared rodent prey on winegrape vineyards in Napa California with and without occupied barn owl nest boxes. We collected data before the breeding season, when hunting pressure should be light, and again when adult owls were hunting actively to feed their chicks. I used the open-hole method to quantify an index of gopher activity, and Sherman live traps to estimate the abundance (minimum number alive) of other rodents. I found that gopher activity declined from before to peak hunting pressure on the vineyard with barn owl nest boxes, whereas it slightly increased on the vineyard without nest boxes. Live trapping revealed that the abundance of mice declined from before to during peak hunting pressure, but this decline was not significantly affected by the presence of nest boxes. Results were inconclusive for voles because they were not well-sampled by our live trapping method, even though analysis of owl pellets confirmed they are an important source of prey for barn owls. This is among the first work in the United States to confirm that barn owl nest boxes can reduce the activity of gopher pests in agriculture. Future work should replicate this study after adding nest boxes to the vineyard that lacks them and employ another method to assess vole abundance or activity.

Citation Style



Thesis/Project Location


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