Seven rugged mountain ranges are separated by broad flat valleys of creosote-bursage that is dissected by desert washes covered with mesquite, palo-verde and ironwood. Lava flows as old as two million years extend into the south-central portion of the refuge, an extension of the geologically famous Pinacate volcanic field in Sonora, Mexico. Saguaros loom in stark profile above the baked earth. The refuge encompasses 860,000 acres, most of which has been designated wilderness. Its 56-mile border with Sonora, Mexico, might well be the loneliest international boundary on the continent.
This landscape is big and wild and can be incredibly hostile to those that need water to survive. Yet within this harsh environment life persists, even thrives. The refuge is home to more than 275 different species of wildlife. Endangered Sonoran pronghorn and lesser long-nosed bats call this parched land home, as do desert bighorn sheep, desert tortoises and many other species of lizards, snakes, and even a few toads. Many birds migrate through the area during spring and fall. The migrating warblers, swallows and flycatchers find food and shelter along the refuge’s vegetation-lined washes. Others birds reside here year-round, including elf owls that peer from holes carved in the saguaros by Gila woodpeckers.
Far from a barren desert, Cabeza Prieta National Wildlife Refuge harbors nearly 400 plant species. For thousands of years, runoff from the mountains during summer monsoons and winter rains eroded into the valleys below bringing sand, silt and gravel. These soils support the plant community known as the creosote bursage flats, broad flats on gently sloping hillsides that support creosote bushes, white bursage, mesquite, palo verde, ironwood, ocotillo and an abundance of cacti, including cholla, and saguaro. Depending on the amount of rain the desert receives during the fall and winter, the spring flower show can be spectacular with more than 30 species flowering at once.
Almost all of Cabeza Prieta National Wildlife Refuge is designated wilderness. It is part of the National Wildlife Refuge System, a national network of lands and water managed for the benefit of wildlife by the U.S. Fish and Wildlife Service.