PRESENCE AND DISTRIBUTION OF MEXICAN OWLS - A REVIEW

Mexico has a rich owl assemblage, represented by 27 species. Eighteen of these species occur in the Nearctic and Neotropical regions, and ni ne species occur only in the Neotropical region. Their biology, ecolog y and distribution, however, are poorly known. We recorded 3683 specim ens collected between 1840 and 1991 from 11 national and 37 foreign mu seums, and reviewed the literature concerning these owls. From these d ata we present a more unified distribution of Mexican owls. Four speci es, Barn Owl (Tyto alba), Great Horned Owl (Bubo virginianus), Ferrugi nous Pygmy-Owl (Glaucidium brasilianum) and Burrowing Owl (Speotyto cu nicularia), have a wide distribution. The Balsas Screech Owl (Otus sed uctus) is endemic to the central Pacific region. Oaxaca and Michoacan had the highest owl species richness with 21 and 19 species, respectiv ely. Aguascalientes, Campeche and Tlaxcala had the lowest owl species richness, four, five, and five respectively. The Ferruginous Pygmy-Owl was the most collected owl, representing 30.7% of the specimens, and the Unspotted Saw-whet Owl (Aegolius ridgwayi) the least with 0.19%. O f the Neotropical species, the Unspotted Saw-whet Owl, Striped Owl (As io clamator), and Stygian Owl (A. stygius) are considered endangered b y the Mexican government. The screech-owl group (Otus) and the Barred Owl (Strix varia)/Fulvous Owl (S. fulvescens = S. v. fulvescens) have uncertain distributions due to taxonomic uncertainties.