Th Cinereous owl (Strix sartorii), a Mexican pine forest endemic, has long been considered a subspecies of the Barred owl (S. varia). in this study, we provide the fist description and analysis of its vocalizations, which diffr markedly from those of the Barred owl and support the recognition of the Cinereous owl as a full species. its rhythmic song consists of seven primary notes and three secondary notes, whereas the analogous song of the Barred owl consists of six primary notes and two secondary notes, arranged in a diffrent pattern. Th rhythmic song of the closely related Fulvous owl (S. fulvescens) has only fie or six primary notes, versus seven in that of the Cinereous owl. Th Cinereous owl’s song is much lower in
pitch than the Fulvous owl’s. Unlike the Fulvous owl but like the Barred owl, the Cinereous owl also has a distinctive and frequently deployed series song.