Giant cacti are the calling card of Saguaro National Park near Tucson, Ariz. The park is named after North America's largest cactus species, the giant saguaro. These cacti grow only in the Sonoran Desert in the U.S. Southwest and in Mexico. Some saguaros soar up to 70 feet (20 meters) in height.
Crane your neck up at a saguaro and you might find nesting critters. Great horned owls are saguaro aficionados, as the above image shows. These owls are among the world's most adaptable owls, living in mountains, deserts, rain forests, rocky coasts and mangrove swamps. Deserts are a good fit for owls because they can nest high in a giant saguaro and hunt over the open desert landscape.
Great horned owls will nest either in the crooks of saguaro cacti or inside holes hollowed out by other animals. Gilded flickers and Gila woodpeckers will excavate inside the saguaro's pulpy flesh. Once a woodpecker looses interest in a cavity, owls, purple martins, finches and sparrows move in.