The Wildlife of Arizona's Sky Islands

South-eastern Arizona’s ‘Sky Islands’ are among the most biodiverse areas in the world and the meeting point of four major North American ecosystems: the Rocky Mountains to the north, the Sierra Madre Mountains to the south, the Sonoran Desert to the south-west and the Chihuahuan Desert to the south-east. These isolated mountain massifs, and the encircling deserts in which they are marooned, offer a wonderful blend of lowland and montane climates and habitats, harbouring a biodiversity unrivalled anywhere else in the United States.

During the late summer rainy season the region’s birds, reptiles and mammals benefit from a ‘second spring’ and a much-needed increase in food availability. Mammals, including Collared Peccary, White-nosed Coati, Cliff Chipmunk and Pronghorn, all take advantage of this season, as do reptiles such as Western Diamondback Rattlesnake and Gila Monster. Since the rains also trigger a second flowering, this is the time to enjoy the greatest diversity of iridescent hummingbirds and colourful butterflies. In total, over 450 bird species (including a variety of Mexican vagrants), 3,000 species of plants, approximately 300 butterfly species and more than 100 species of mammals have been recorded in the Sky Island area.

Arriving in Phoenix, Arizona, we head southeast towards Tucson and the Sky Islands. We begin with a 2-night stay at the beautiful Tanque Verde Ranch, nestled within Saguaro National Park, where the surrounding rocky desert hills are covered in huge Saguaro Cacti. From here we explore the high peak of Mount Lemmon, the highest point in the Santa Catalina Mountains. As we climb in altitude the temperature gradually drops and precipitation increases, creating a gradation of different habitats from the desert scrub of the lowlands to oak woodland and then Ponderosa Pine, fir and spruce forests higher up. Driving up from the Sonoran Desert into the cool Rocky Mountain forests is like travelling from Mexico to Canada in a single morning! Along the way we will look for a variety of different mammals including Harris’ Antelope Squirrel, Mule Deer and Cliff Chipmunk, and such birds as Greater Peewee, Yellow-eyed Junco and Zone-tailed Hawk.

Next, we head further south, spending two nights in the Madera Canyon. Here we make a special search for the beautiful Elegant Trogon, and will include a stop at the Santa Rita Lodge, famous for its sugar-water, suet and seed feeders. A kaleidoscope of hummingbirds is usually seen here, along with Mexican Jays and Acorn Woodpeckers, and, as dusk falls, White-nosed Coati, Ringtail and Northern Racoon are also attracted to the feeders.

After a night spent close to the Mexican border, allowing us to explore the deserts around Patagonia, we will spend the next four nights in the Huachuca Mountains at a nationally acclaimed ‘birding inn'. Here we will explore the nearby canyons in search of Mexican Spotted Owl, Pyrrhuloxia, Rufous-capped and Grace's Warblers and 12 species of hummingbird! Close-up encounters with such butterflies as the mint-green Arizona Hairstreak and Zela Metalmark are common, whilst Two-tailed Swallowtails and Arizona Sisters dazzle us overhead. Multiple squirrel and rabbit species are possible, and up to three species of skunk are frequently encountered. Rarer sightings include Bobcat, American Black Bear and Mountain Lion.

During our stay in the Huachuca Mountains we will also visit the San Pedro Riparian National Conservation Area, the best example of the desert riparian ecosystem in the United States. With its 80 recorded species of mammals and 40 reptiles and amphibians, the San Pedro Riparian NCA is one of the most diverse reserves for vertebrates in the whole of the continental United States. Over 180 species of butterfly have also been recorded in this reserve and it was the first ‘Important Bird Area’ listed in the United States, acting as a migratory corridor for an estimated four million birds each year!

The Chiricahua Mountains — the largest of the Sky Island ranges — will be our final stop on this tour, and we will spend two nights there at the wildlife-focused Cave Creek Ranch. This mountain range is home to six different plant communities, including high-elevation Mexican pine-oak woodlands, the only place in the United States where this habitat exists. Each of these six communities support a unique subset of wildlife, marking, for some, the northernmost limits of their range. We will spend these last two days exploring the many trails here in search of Mexican Chickadee, Montezuma Quail and Lucifer Hummingbird, and relaxing whilst we enjoy the busy hummingbird feeders and bird tables. Finally, we must start our return journey north to Phoenix, stopping for a night back near Saguaro National Park en route, and from there fly home.