It’s the most romantic name in the world for a mountain: sky island. The two words conjure up a magical, lofty kingdom from Avatar or your favorite children’s book, and though they’re surrounded by land and not water, they possess all the island essentials. They are separate. They follow their own rules. And they are hard to get to.
Rising from sparse grasslands or deserts, sky islands aren’t hard to define. They’re isolated peaks, shooting up out of the flatlands like the first stalks of corn in a summer garden. And they rise in more than one corner of the American West: from volcanic Mt. Rainier in Washington to Mt. Lassen in California to Nevada’s Mt. Charleston, part of Spring Mountains National Recreation Area. Perhaps the least-known natural wonders, these heights are beautiful, unique, and life-sustaining for thousands of plants and animals. Naturalist Weldon Heald coined the term in his 1967 book Sky Island, writing romantically about his beloved Chiracahua Mountains in Arizona. The designation proved so poetically apt that it was later given to an entire group of isolated ranges that extends from Arizona and New Mexico deep into Sonora, Mexico. That broken chain—55 mountains in all—is called the Madrean Archipelago, and it’s among the largest grouping of sky islands on earth.
Serving as bridges between the Rocky Mountains and Mexico’s Sierra Madre, and between the Sonoran and Chihuahuan deserts, the Madreans are “one of the most biologically diverse places in the contiguous United States,” says Louise Misztal, executive director of the Sky Island Alliance, a Tucson-based organization that works to protect and restore the biodiversity of the region. “Half of the bird species in North America can be found here at some point during the year. There are a dozen different species of hummingbirds. And so many different bees.”
Part of the allure of a Southwestern sky island is the element of surprise. As I drive across southern Arizona on I-10, they loom in the distance, ridged and wrinkled, denim blue or coffee brown depending on the light, and seemingly not that distinct from the desert around me. I pull off the interstate in Tucson and take the Sky Island Scenic Byway (aka the Catalina Highway) toward Mt. Lemmon, the highest point in the Santa Catalinas. At the base lies the saguaro-and-brittlebush landscape of the Sonoran Desert. But as the highway twists and climbs, the world transforms. It grows greener and cooler, the saguaros replaced by cottonwoods and oaks, then, near the summit, by stands of ponderosa pine. The 27 miles take me up 6,000 feet through four distinct life zones—desert, grasslands, woodlands, and forest. I may as well have driven from Mexico to Canada.
Once at Lemmon’s summit, I step out of the car, pull on a fleece jacket, and gape. Spreading far below is what looks to be the entire Southwest. Arizona is not short on scenic wonders—there’s that big canyon in the state’s northwest corner, for example. But no place has given me a greater sense of infinity.
Sky islands aren’t just for birds and gawking motorists. Beyond the winged creatures that make homes here in the Madrean Archipelago are four species of cat. Two are common: the mountain lion and the bobcat. A third, the ocelot, is rare. The fourth, the jaguar, is extremely scarce and serves as a potent symbol of the Madrean’s ecological importance. Jaguars might call to mind images of tropical rain forests, but the northern limit of their reach actually includes parts of Arizona and New Mexico. They’ve long been considered endangered in the United States. Now, to the excitement of wildlife biologists like Sergio Avila of Sierra Club Outdoors—who has studied sky islands for the past 15 years—they seem to be making a tentative comeback. “For the last two decades, we’ve had at least one jaguar sighting in the Madrean sky islands every year,” he says. “It’s where black bears and jaguars meet. Nature is a series of collected elements. And the Sky Islands are so rich because they have so many different elements.”
Back on Mt. Lemmon, jaguars are unlikely sights—they are famously nocturnal and stealthy. But there are hummingbirds and squirrels and deer, as well as that soaring view that makes it all feel untouched by what goes on down below.
Unfortunately, in 2018, these heights aren’t as preserved as they seem, and the Madrean Archipelago is under threat as never before. The first concern lies on the land that separates each mountain. Many of the animals of the archipelago depend on wildlife corridors, pathways they take to travel from one island to the next to get food and to breed. As the Southwest becomes more urbanized, these corridors are increasingly blocked by homes, shopping centers, and freeways, leaving each island’s population of animals isolated and less robust.
Then there’s the biggest roadblock of all: the border infrastructure—including a wall as high as 30 feet in many places—along the Mexico/United States line that disturbs water courses, normal migratory paths, and the habitat of plants and animals. “Nature has no borders. Jaguars don’t know if they’re in Arizona or Mexico,” says Avila. “They don’t have passports.”
Experts like Misztal and Avila think the current wall (along with any future expansions) is one of the most immediate threats the Southwest’s sky islands face. Another serious one is global: climate change. “They’re in one of the fastest-warming regions in the nation,” says Misztal. “And they’re already in one of the driest. As we see increased temperatures, the region is getting drier, water is getting scarcer. Wildfires are getting bigger and more intense, and after a fire, the land may never return to forest, but convert to scrublands.” And the effects are already showing. “We’re seeing changes in vegetation. Flowers bloom earlier, and when the migratory birds and butterflies that depend on them for food arrive, they’ve missed the bloom,” says Avila. “Animals can’t adapt fast enough.”
Even so, the prognosis for these peaks is not necessarily fatal. Misztal points out that it is possible to have residential and retail development that preserves wild- life corridors—Pima County, home to Tucson, has done that with its Sonoran Desert Conservation Plan, for example. Then there are the efforts by groups such as the Sky Island Alliance. Backed by its cadre of scientists and hundreds of volunteers, the organization works on land-restoration projects—such as replanting after wildfires—that help animals and ecosystems adapt to a warming world. “We’re trying to buy some time,” says Misztal. “I hope people who haven’t visited still have a chance to see them. To appreciate what they are.”
Back on top of Mt. Lemmon, I linger longer than I anticipated. It’s that view from the rocky summit down at the rumpled planet below. How, I think, can anyone live their life without that image of sheer vastness? I balk at getting back in the car to leave, the way I used to pause before reading the last page of that favorite children’s book, as if I don’t ever want the story to end.
Mt. Charleston Day Trip
Next time you’re in Las Vegas, put the bright lights in your rearview and drive 45 minutes to Mt. Charleston. Here, 60 miles of trails wander through bristlecone and ponderosa pines that were tiny saplings during the days of King Arthur.—Anne Burke
Eat: Fuel up for the day with buttermilk pancakes at Mt. Charleston Lodge (mtcharlestonlodge.com), perched on a mountainside at 7,717 feet.
Geek Out: What are limestone cliffs doing in the middle of a desert? Get answers at the U.S. Forest Service’s hugely fun and informative Spring Mountains Visitor Gateway (gomtcharleston.com).
Hike: From the Visitor Gateway, the 2.6-mile Acastus Trail weaves through pines and aspens. Should the altitude get to you, take advantage of the occasional benches.