Sonoran Desert Toad (Incilius alvarius) is the largest (18 cm) native toad in the U.S. and occurs in Arizona, New Mexico, and possibly California. They are found in a variety of arid habitats, but in New Mexico are restricted to desert shrublands and grasslands in the southwestern portion of the state. Unlike many arid land amphibians, the Sonoran Desert Toad is not dependent on rainfall for breeding, though precipitation does increase activity levels.