Fish and Wildlife Service, Arizona.
A journey into the third largest wildlife refuge in the lower 48 states takes plenty of water and desert survival skills. Almost all of Cabeza Prieta National Wildlife Refuge is designated wilderness. Seven rugged mountain ranges cast shadows above valleys dotted with sand dunes and lava flows. The 1,000-square-mile refuge shares a 56-mile international border with Sonora, Mexico.
Temperatures may top 100 degrees for 90 to 100 straight days from June to October. Summer thundershowers and winter soaking rains average about 7.5 cm on the western part of the refuge and up to 20 cm on the east side, 60 miles away. The winter and summer pattern of rainfall in the Sonoran desert stimulates the growth of more plant species than in most deserts. You'll find creosote bush flats, bursage on the bajadas, mesquite, palo verde, ironwood, and an abundance of cacti, including ocotillo, cholla, and saguaro.
Endangered Sonoran pronghorn and lesser long-nosed bats call this parched land home, as do desert bighorns, lizards, rattlesnakes, and desert tortoises. Elf owls peer from holes carved in saguaros by Gila woodpeckers. Every plant and animal has adapted to life we would find uninhabitable. Far from a barren desert, Cabeza Prieta NWR harbors as many as 420 plant species and more than 300 kinds of wildlife.
Cabeza Prieta, Spanish for "black head," refers to a lava-topped, granite peak in a remote mountain range in the western corner of the refuge.
Cabeza Prieta NWR refuge office/visitor center is in Ajo, in southwestern Arizona.
From Phoenix: Take I-10 west to exit 112, follow Highway 85 south to Gila Bend, continue south on 85 approximately 40 miles to Ajo.
From Tucson: Take Highway 86 (Ajo Way) west across the Tohono O'odham reservation to Why, follow Highway 85 north to Ajo.
From Yuma: take I-8 east to Gila Bend, follow Highway 85 south approximately 40 miles to Ajo.
The refuge office is on the west side of the highway at the north end of town.