The Big Morongo Canyon Preserve is a 31,000-acres (130 km2) native plants habitat and wildlife preserve located in the Little San Bernardino Mountains of the Transverse Ranges, in the transition zone between the higher Mojave Desert and lower elevation Colorado Desert section of the Sonoran Desert. Due to its location within this transition zone, the area is especially high in natural diversity. The natural spring fed desert oasis found here is one of the 10 largest Cottonwood (Populus fremontii) and Willow (Salix lasiolepis) riparian habitats in California. It is also identified by the Audubon Society as one of the most important avian habitat areas in California.