HOW DOES LANDSCAPE COMPOSITION AFFECT FORGING PATTERNS OF BARN OWLS (TYTO ALBA) IN AN URBAN-AGRICULTURAL SETTING OF CALIFORNIA?

Xeronimo A Castaneda; Humboldt State University; xac11@humboldt.edu; Matthew D. Johnson

Large-scale conversion of natural land to agriculture threatens wildlife and can diminish ecosystem services provided by nature. Understanding how wildlife can provision ecosystem services may incentivize wildlife conservation in agricultural landscapes. Attracting barn owls (Tyto alba) to nest on farms for pest management has been documented worldwide but has not been thoroughly evaluated in vineyard agroecosystems. Napa Valley, California is a renowned wine-grape growing region where viticulturists encourage barn owl occupancy to help minimize plant damage from pocket gophers (Thomomys bottae) and voles (Microtus californicus). Our study aims to establish a basis for revealing the abilities of a predator to provide an ecosystem service to farmers by modeling space and time use of selected habitats. From location data obtained of nesting owls we constructed intensity of use and home range-movement maps using a Time Local Convex Hull (T-LoCoH) analysis. Models determined barn owls preferred natural habitats for foraging and used vineyards proportionally to their availability. Additionally, models that decreased the amount of preferred natural habitat showed an increase in owl use of vineyards. Therefore, there appears to be a trade-off from farmer and conservationist perspectives. Future modeling should examine if there is an optimal landscape composition that balances the amounts of natural habitats and vineyard foraging.

Ecology and Conservation of Birds I