Skip to main content

U.S. Forest Service

Sky Islands

Join Us to Discover

“Sky Islands” are isolated mountain ranges in southeastern Arizona and northern Mexico. Some of the mountains rise more than 6,000 feet above the surrounding desert floor making the lowlands and high peaks drastically different. Plants and animals living in the mountains could never survive in the surrounding deserts. Thus by analogy, the mountains are “islands” surrounded by deserts that are “seas”.

Map of the sky island areas.

What are Sky Islands?

Sky Islands are isolated mountain ranges in southeastern Arizona and northern Mexico, connecting two very different mountainous regions. Sky Islands are places where you can see incredible plant diversity in only a few miles.

Erigeron saxatilis.

Climate Changes and Evolving Plants

About 20,000 years ago, North America was in an Ice Age. In the Southwest, there was less desert and more woodlands than today. As the climate grew hotter and drier, plants and animals were trapped and isolated on Sky Island mountainsides, a recipe for plant evolution.

Oak-pine forest community.

Sky Island Plant Communities

When you climb a Sky Island mountain in the summertime, you start in the desert where the daytime temperature may reach 120° Farenheit and you end up on a mountaintop where the temperature is perhaps 75° Farenheit and you feel comfortable wearing a jacket.

Coronado National Forest sign.

Sky Islands of the Coronado National Forest

The Coronado National Forest in southeastern Arizona manages major parts of the Sky Islands north of Mexico. Habitats vary from deserts to subalpine forests. The high elevation peaks are refuges for plants, animals, and even humans when temperatures soar in the deserts.

Datura wrightii.

Plants of the Sky Islands

There are many diverse and unusual plants growing in the Sky Island plant communities. Enjoy a small sampling of these species.