Multi‐year nest box occupancy and short‐term resilience to wildfire disturbance by barn owls in a vineyard agroecosystem

Abstract

AbstractLandscape composition can strongly affect the delivery of ecosystem services in agroecosystems. Conserving uncultivated habitats can support ecosystem services, but in Mediterranean biomes, these lands can also increase the area susceptible to wildfires. In the world‐renowned wine‐producing region of Napa Valley, California, wine grape growers install nest boxes to attract American barn owls (Tyto furcata), which may reduce rodent crop damage. Annual monitoring of 273 nest boxes began in 2015, and devastating wildfires burned approximately 60,000 ha in the region in 2017, including homes and businesses, as well as some vineyards and uncultivated land. The goal of this study was to determine whether changes in nest box occupancy were attributed to wildfires, nest box design, land cover type, or some combination of these variables. Occupancy surveys before and after these wildfires revealed changes in habitat selection at the nest scale. Occupancy increased during the study, reaching its highest point after the fires. Owls were found breeding in recently burned areas that were previously unoccupied and modeling results showed that nest box occupancy had a positive relationship with burned areas, particularly with edges of the fire perimeter. Barn owls also consistently showed a strong preference for taller nest boxes that were surrounded by more grassland than other land cover types and a moderate selection for wooden over plastic boxes. These results illustrate an incentive for the conservation of uncultivated habitat, particularly grassland, in vineyard ecosystems, and they provide an example of a mobile pest predator’s response to wildfire disturbance. In this case, results suggest an agroecosystem service made resilient to wildfire by the owls’ selection of burned and uncultivated habitats.