The Sonoran Desert is a 100,000 square mile (260,000 square kilometers) arid region in North America that stretches across large portions of Arizona, California, and the northwest Mexican states of Sonora, Baja California, and Baja California Sur. Although it is the hottest of the four North American deserts, its distinct bimodal rainfall (raining heavily both in the summer and winter) makes the region extremely biologically developed and diverse. The Sonoran Desert is home to some of the most unique animal and plant life in North America, many of which cannot be found anywhere else. For example, the only remaining jaguar population in the United States (estimated between 80 to 120 jaguars), can be found in the Sonoran Desert. Other more well-known animals include roadrunners, gila monsters, cactus wren, and desert bighorn sheep.