Amargosa Canyon

This area is of exceptional import zoologically and is of interest geologically and paleontologically. It includes Willow Springs, China Ranch and a 19-kilometer (12-mile) stretch of the Amargosa River south of Tecopa. In the Amargosa Canyon the river flows above ground year round, creating an "ecological island" isolated from the rest of the desert by geographical and climatic barriers. A number of endemics, including several rare or endangered species, occur in this area, as do more widely distributed plants and animals.

Along this segment of the river is the type locality of the Amargosa pupfish, Cyprinodon nevadensis amargosae. The springs in the area may harbor populations of the Tecopa pupfish, Cyprinodon nevadensis calidae, probably extinct elsewhere. The canyon also contains a local race of the uncommon speckled dace, Rhinichthys osculus.

Among the score or more of mammals recorded here are several species of mice and kangaroo rats, the endemic pocket gopher, Thomomys bottae amargosae, desert kit fox, Vulpes macrotis, ringtail, Bassariscus astutus, and the bobcat, Lynx rufus. Although declared extinct in 1917, the endemic Amargosa meadow mouse, Microtus californicus scripensis, was collected here in 1936.

Over 220 species of birds have been identified in the area, including 11 raptors, among them the endangered prairie falcon, Falco mexicanus. With over two dozen ducks and shorebirds noted, it is an important desert stop for migrants. Unusual sightings here include Crissal thrashers, Taxostoma dorsale, Virginia warblers, Vermivora virginiae, and breeding Lucy's warblers, Vermivora luciae, goshawk, Accipiter gentilis, and black-throated blue warbler, Dendroica caerulescens.

Over 40 species of reptiles and amphibians may be found in the area.

Although the area has not been intensively surveyed entomologically, it may support a number of highly restricted endemic species. A crayfish, still undescribed, was discovered in this area, the first occurrence of any crayfish in the California desert.

In the Canyon, which ranges from 120 to 600 meters (400 to 2,000 feet) in width, are the China Ranch beds, a series of light-colored, mainly white to dazzling pink saline claystones with some inter-bedded gypsum layers. Nearby, downcutting by the river has exposed Precambrian rock which forms the probable basement through much of this area. This rock, which has been altered by mineralized solutions, has become extremely colorful.

Within the area there are several fossil beds which, with nearby beds, provide the first good record of middle Pleistocene life from the Mojave Desert.

Integrity: A portion of the area is grazed, and there are scattered mining sites. The old Spanish Trail passed through the canyon, and remnants of the Tonopah & Tidewater Railroad are visible. Some damage has occurred as the result of off-road vehicles.

Use: Research, education, light recreation.

Ref: Romero, W. A., et al. 1972. Amargosa Canyon-Dumont Dunes Proposed Natural Area. Pupfish Habitat Preservation Committee, Montrose, California.

February 1975