The topography of the area surrounding Tucson in southeastern Arizona, in southwestern New Mexico, and in northern Sonora, Mexico is of great interest to biologists because there are many "islands" of raised land that project upwards out of the Sonoran Desert. These islands are “stepping stone” from the Rocky Mountains of the United States to the Sierra Madre mountains of Mexico. The “islands” are often widely separated from each other by many miles of dry and hot desert with many species of cactus and arid adapted plants. The islands themselves, rising to nine or 10 thousand feet, are wetter, cooler, and have lush vegetation zones from oak and juniper up through pines, to fir and sometimes spruce at the top. Because each island is ecologically isolated, some species cannot easily move from one island to another (for example plants, lizards, non-flying insects, and small mammals). However, birds, bats, flying insects, and plants that propagate by seeds that are carried by the wind, may be the same in all neighboring islands. Madera Canyon, while only one of many canyons in the archipelago of desert sky islands, is the most studied and the most easily accessible canyon to the public. At the same time, its environment and its flora and fauna are protected and available for all visitors to enjoy.
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