Covering nearly 47 million acres in the American Southwest and northern Mexico, the Sky Islands region is named after its signature sky islands — forested mountain ranges rising from a sea of desert flatlands.

It is one of the most biologically diverse places in the world, where temperate and subtropical zones come together. A ribbon of green winding through the arid land, the San Pedro River is the last undammed river and one of the most important migratory flyways in the Southwest for 300 species of birds, 200 species of butterflies and 20 species of bats as they fly from Central and South America and back.

There are at least 41 endangered species in the Sky Islands region, including the jaguar, ocelot, Mexican gray wolf, thick-billed parrot, New Mexican ridge-nosed rattlesnake and Apache trout.


A major threat to the sky islands is the construction of a border wall. A major threat is ongoing construction of the border wall, which splits populations of some animals into separate U.S. and Mexican populations. This is particularly harmful for species like jaguars that are already endangered, species like pronghorn that must migrate long distances to survive, and species that must shift their ranges north to cope with climate change. Other land use, like increasing mining, urban development and highways, degrade habitat and soil. Decades of fire suppression and livestock grazing have changed the natural regime of periodic fires here as well, and more frequent and less intense fires are needed to restore the natural systems that evolved over time. 

Defenders' Impact

Defenders is engaged on Capitol Hill and in the courts to stop border wall construction.

We published a ground-breaking report In the Shadow of the Wall that explains how the wall would affect five critical conservation hotspots — areas with great biodiversity and immense investment in protected lands. Over 3,000 scientists from over 50 countries expressed unified concern over the border wall’s negative impacts on biodiversity and binational conservation by signing the article "Nature Divided, Scientists United: U.S.-Mexico Border Wall Threatens Biodiversity and Binational Conservation," published in the journal Bioscience.

On the ground, Defenders is working to improve the ecological integrity of federal and tribal lands, including the Apache-Sitgreaves, Gila and Coronado National Forests, within the Sky Islands region to boost populations of important wildlife species. In turn, these species, particularly predators, can help improve the health of the ecosystem.

We are concentrating our efforts on forest planning and putting a stop to destructive, new mining operations. Defenders works to curtail mining in the Santa Rita and Patagonia ranges, and we partner with a wide range of grassroots, citizens groups to track development and protect wildlife and habitat in this sensitive region.

Wildlife and Wild Places

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