Graduation Date

Fall 2019

Document Type

Thesis

Program

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

Committee Chair Name

Matt Johnson

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

William "Tim" Bean

Second Committee Member Affiliation

Community Member or Outside Professional

Third Committee Member Name

Dan Barton

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Wildlife Management

Abstract

Wine producers in Napa Valley, California install barn owl (Tyto alba) nest boxes in vineyards with the goal of reducing rodent crop damage. Previous research has shown that the probability of attracting barn owls to nest boxes and encouraging them to hunt in vineyards is strongly influenced by the design of the nest box itself and the composition of the surrounding landscape. In 2017, wildfires in the Napa area burned nearly 60,000 ha, primarily affecting urban areas, which caused human devastation, and uncultivated habitats, which barn owls are known to select. Data collected before the fires on nest box occupancy and hunting habitat selection allowed for a comparative analysis of barn owl behavior before and after the fires. I analyzed four years of occupancy data on 273 nest boxes, finding that nest box occupancy was consistently associated with tall, wooden nest boxes that face away from the sun and have grassland and riparian land cover within the average hunting radius of the nest box. Additionally, wildfires increased nest box occupancy and modeling showed that the probability of a box becoming occupied after the fires was positively associated with the amount of fire edge within the average hunting radius of the nest box. I also analyzed GPS tracking data on 32 birds nesting in 24 individual nest boxes, with data collected before and after the fires. I found that barn owls are most likely to hunt in vineyard, grassland, riparian, and oak savannah land cover types and areas closest to the nest box, and these results were not affected by fire. Barn owls did show some hunting habitat selection for burned edges and low to intermediate severity burned areas, but their land cover type selection was resilient to landscape changes caused by wildfires. The combination of occupancy and hunting habitat selection analysis can be used to provide broad and durable guidance to wine producers who use barn owl nest boxes. With fires increasing in the western United States, the short-term resiliency of barn owls to the landscape changes caused by fires can have positive implications for their ability to provide pest control.

Citation Style

The Condor

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