Distribution of Birds and Plants at the Western and Southern Edges of the Madrean Sky Islands in Sonora, Mexico

The western and southern edges of the Madrean Sky Island region are poorly defined and have received little study. After exploring mountains in these areas, we documented range extensions and additional records for several species of interest. Although many of these disjunct mountains have not been considered Sky Islands, their flora and fauna are similar to other areas within the region. Therefore, we suggest their biota indicate they require inclusion as part of the Madrean Sky Island region. Distribution and abundance of organisms within our study areas should be carefully inventoried while they remain relatively unaltered from human actions.