The University of Arizona

Rain Gods in a Desert Sea: New Book Celebrates Southern Arizona's Mountains

By Daniel Stolte, University Communications | July 11, 2013

A book by two UA scientists explains the story behind the scenery of the "sky islands," the unique mountain ranges dotting southern Arizona and northern Sonora, Mexico.

Coveted by southern Arizona residents as refuges from the summer heat, the sky island mountain ranges are hot spots of biodiversity. (Photo: Shelley Littin/UANews)
Coveted by southern Arizona residents as refuges from the summer heat, the sky island mountain ranges are hot spots of biodiversity. (Photo: Shelley Littin/UANews)
Doubling as a coffee table book and a field guide, "A Natural History of the Santa Catalina Mountains, Arizona" offers an easy-to-read and richly illustrated introduction to the natural history of the sky islands.
Doubling as a coffee table book and a field guide, "A Natural History of the Santa Catalina Mountains, Arizona" offers an easy-to-read and richly illustrated introduction to the natural history of the sky islands.
The book includes a guide for a drive up Mount Lemmon Highway, explaining the natural features at different stops. (Photo: Richard Brusca)
The book includes a guide for a drive up Mount Lemmon Highway, explaining the natural features at different stops. (Photo: Richard Brusca)
From southern Mexico to Alaska - all in one mountain. In the sky island mountain ranges, going up 1,000 feet in elevation is like traveling 300 miles to the north. The tallest mountains in the area contain 8 different life zones or "biomes," each with their own vegetation and fauna. (Illustration: Wendy Moore)
From southern Mexico to Alaska - all in one mountain. In the sky island mountain ranges, going up 1,000 feet in elevation is like traveling 300 miles to the north. The tallest mountains in the area contain 8 different life zones or "biomes," each with their own vegetation and fauna. (Illustration: Wendy Moore)
University of Arizona scientists Wendy Moore and Richard Brusca have published an illustrated book to celebrate and share the rich and unique natural history of southern Arizona's mountains – the "sky islands" – with a general, non-scientific audience. 
 
Moore, assistant professor in the department of entomology in the UA College of Agriculture and Life Sciences and curator of the UA Insect Collection, said the book came about through field research she began two years ago when she founded the Arizona Sky Island Arthropod Project (ASAP). For her field research, Moore enlisted the help of Brusca, who is her husband as well as executive director emeritus of the Arizona-Sonora Desert Museum and an adjunct research scientist in the UA's department of ecology and evolutionary biology
 
"We collected a lot of background information about this region and needed to understand more about its biodiversity," she said. "We needed to take photos of the flora and fauna, and so we decided to turn all that into a book for the public. A book for the people who live in this area, so they can appreciate this landscape more fully by understanding this beautiful place in which we live."
 
Although "A Natural History of the Santa Catalina Mountains" focuses on the Catalina Mountains just north of Tucson, its scope includes all "sky island" mountain ranges in southern Arizona and northwestern Mexico. 
 
"Our book uses the Catalina Mountains as the archetypical mountain range for southern Arizona because it is the one that's best known and most accessible, but you could take it to any mountain range in our area," Brusca said.
 
Especially in the summer, the sky islands lure visitors looking to escape from the heat of the lowland desert in southern Arizona. That's because for every 1,000 feet of elevation gain, the reader learns, the temperature drops about 4 degrees, and annual precipitation increases about 4.5 inches – the equivalent of driving 300 miles north. 
 
The magic of the sky islands lies in what biologists call stacked biomes. The mountains contain the same variety of climate, vegetation and fauna one would encounter while traveling from Mexico to Canada, all compressed into several narrow ranges of elevation, rising from the subtropical desert around Tucson to subalpine forests at the top of Mount Lemmon at 9,157 feet.  
 
Moore said she enjoys combining scientific research, teaching and creative approaches to getting the public – especially children – excited about the outdoors and the natural world. Those interests, and particularly her research project aimed at assessing the biodiversity of arthropods – insects, spiders, scorpions and such – in the sky island region spawned the idea for the book. 
 
She said the sky islands are a hot spot of biodiversity and researchers can look at them to study the processes underlying species diversification. 
 
"What makes this region so special is the fact that it represents the only gap in what is often referred to as the 'spine of the continent' or the North American Cordillera – a continuous chain of mountains running from southern Mexico to Alaska. Scattered in this gap are 65 mountain ranges, like islands rising from a desert sea." she said
 
Moore said arthropods are especially interesting because they have short lifespans and reproduce frequently, and therefore adapt faster to changes in climate and habitat than other groups, such as reptiles or mammals. Populations isolated from each other on scattered mountaintops quickly can develop into separate populations and ultimately diverge into different species. 
 
With abundant photographs and easy-to-read text, the book starts with an overview of the sky islands and what makes them one of very few places in the world where such great biodiversity and variety in life zones are readily apparent to anyone willing to go out and explore. 
 
"The book is spiral-bound because we want people to take it with them in the field and use it, not leave it at home," Moore said. "We hope that it stimulates a lot of research and public interest in the sky island region."
 
The authors credit their editor, Linda Brewer at the Arizona-Sonora Desert Museum Press, with going above and beyond in publishing this book.
 
"I'm so much happier with this book than I ever thought I would be because of the attention she gave to the production," Moore said. 
 
The chapters provide an introduction about the sky islands in general, delve into deep time to reveal the geologic forces that have shaped them, tell the stories of the first naturalists who explored their unique natural environments on horseback, and explain how the mountain islands shape the entire area today. 
 
"One of the most fascinating aspects of the mountains to me is that they are in part responsible for our  monsoon rains," Moore said. "Moisture from the Gulf of California sweeps over the dry, low-lying desert, with clouds dumping their rains when they hit the mountains. There is something special about viewing the sky islands as 'our rain gods.'"
 
One of the book's most intriguing parts is a self-guided tour on the Catalina Highway up Mount Lemmon just north of Tucson. 
 
"The Catalinas are the only sky islands that have a paved road to the top," Brusca pointed out, "allowing you to drive through eight biomes in less than an hour. It's one of the very few places in the world where you can actually do that."
 
"At each stop, you'll find yourself in a different biome with very different vegetation," Moore added, "and we orient you to what you're seeing – the age of the rocks there and interesting aspects about the natural history."
 
For those eager to leave the car behind and set out on one of the numerous hiking trails, the book contains a richly illustrated field guide section to help identify the most commonly encountered plants, animals and fungi. 
 
As Brusca and Moore wrote in the introduction, they hope their book will inspire the reader to "pack a picnic lunch, grab your compass, take water and hiking shoes, and leave your cares in the valley below."