Short-Eared Owl Land-Use Associations during the Breeding Season in the Western United States

Abstract

ABSTRACT The Short-eared Owl (Asio flammeus) is a species of conservation concern in the western USA, with evidence for declining population sizes. Monitoring of Short-eared Owls is complicated because of their low site fidelity and nomadic movements. We recruited community-science participants to implement a multi-year survey of Short-eared Owls across eight states in the western USA, resulting in a program of sufficient temporal and spatial dimensions to overcome many of the challenges in monitoring this species. We implemented both multi-scale occupancy and colonization/extinction modeling to provide insights into land-cover use, and to identify which cover types supported higher occurrence. Short-eared Owls were associated with native and anthropogenic land-cover types, but site occupancy varied among these categories and at different scales. Native grasslands, marsh/riparian, hay/fallow agriculture, and cultivated croplands were occupied most consistently across years. Occupancy rates differed at different scales (e.g., marsh/riparian was the only land-cover type positively associated with occupancy at both transect and point scales). Contrary to expectations, native shrubland was negatively associated with occupancy at the point scale, and exhibited low colonization and high extinction rates. Our results suggest that conserving native landscapes in general, and grasslands, marsh, and riparian areas specifically, would benefit Short-eared Owls. Furthermore, Short-eared Owl occupancy was positively associated with hay/fallow land-cover types, suggesting that some nonnative land-cover types can function as Short-eared Owl habitat. Lastly, our results highlight how developing a broad-scale community science survey can inform conservation for a species not well monitored by existing survey programs.