Madrean Sky Islands
The Madrean Sky Islands are enclaves of Madrean pine–oak woodlands, found at higher elevations in a complex of small mountain ranges in southern and southeastern Arizona, southwestern New Mexico, and northwestern Mexico. The sky islands are surrounded at lower elevations by the Sonoran and Chihuahuan deserts. The northern west–east perimeter of the sky island region merges into the higher elevation eastern Mogollon Rim and the White Mountains of eastern Arizona (southern Anasazi region). 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, of the tropical and subtropical coniferous forests biome. 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 Arizona are the Baboquivari Mountains, Chiricahua Mountains, Huachuca Mountains, Pinaleño Mountains, Santa Catalina Mountains, Santa Rita Mountains and Whetstone Mountains. Similar sky island ranges include the Animas Mountains in New Mexico  and the Guadalupe Mountains, Davis Mountains and Chisos Mountains in west Texas. Significant urban areas located very close to the Madrean Sky Islands include Las Cruces, New Mexico, and Tucson, Arizona. Fauna. Though formerly extirpated from the United States, the North American jaguar has returned to the area from northern Mexico in small numbers. One such jaguar is named El Jefe.