Madrean sky islands
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The Madrean sky islands are enclaves of Madrean pine-oak woodlands, found at higher elevations in a complex of small mountain ranges in southern Arizona and New Mexico and northern Mexico. The sky islands are surrounded at lower elevations by the Sonoran and Chihuahuan deserts.
The sky islands are the northernmost of the Madrean pine-oak woodlands, and are classified as part of the Sierra Madre Occidental pine-oak forests ecoregion. The sky islands were isolated from one another and from the pine-oak woodlands of the Sierra Madre Occidental to the south by the warming and drying of the climate since the ice ages.
There are approximately 27 Madrean sky islands in the United States, and 15 in northern Mexico. The major Madrean sky island ranges in the United States are the Baboquivari Mountains, Chiricahua Mountains, Pinaleño Mountains, Santa Catalina Mountains, and Santa Rita Mountains.
