Riparian: There are a approximately 47 reptile species in Grand
Canyon National Park. Ten are considered common along the river
corridor and include lizards and snakes. Reptiles use both
upland desert and riparian sites, but higher densities are
supported in riparian areas due to the rich invertebrate food
source and vegetation. Lizard density tends to be highest along
the stretch of land between the water's edge and the beginning
of the upland desert community. Within this zone, exotic
saltcedar (tamarisk) is abundant, which is excellent lizard
habitat. One can also find gila monsters and chuckwallas here,
the two largest lizards in the Canyon. Many snake species, which
are not directly dependent on surface water, may be found both
within the inner gorge and the Colorado River corridor. Since
many snakes feed on lizards, higher prey densities along the
river probably result in higher snake densities as well. Six
rattlesnake species have been recorded in the park. Two are
species rarely encountered, the South