Ferruginous pygmy-owls in the Sonoran Desert

Ferruginous Pygmy-Owls (Glaucidium brasilianum) are small diurnal birds of prey that have declined to endangered levels in southern Arizona, USA. We assessed resources important to habitat selection and reproductive performance of pygmy-owls at five spatial scales across broad gradients in vegetation structure and aridity in the Sonoran Desert. Resources at the nest-cavity scale explained more variation in selection and performance than those at larger scales, highlighting their importance for conservation. At these small scales, owls selected nest cavities with smaller entrances, larger volume, greater height, and orientations that produced cooler microclimates in the hottest regions of the study area, and these choices all promoted higher performance.