Location: Montezuma CountySize: 443 acres.Designated: March, 1986Land Manager: The Bureau of Land Management
It’s about as far as you can get from Denver and still be in Colorado - about 8 ½ hours of driving and a high clearance vehicle will get you there. Needless to say, it is one of Colorado’s least-visited Natural Areas, but its isolation is a great part of its value. McElmo’s inhabitants thrive on being left alone.
Located on the Utah-Colorado border about 25 miles west of Cortez, the 433-acre McElmo Natural Area occupies Bridge Canyon, a tributary of McElmo Canyon. The setting is typical of the region - a broad, dry, rocky canyon with sparse pinyon-juniper and salt-desert shrub vegetation. Two things set this area apart from its surroundings: the reptiles and the Bridge.
Bridge and McElmo canyons have long been recognized as hotspots of animal biodiversity in Colorado. According to a 1977 report by Bruce Bury and later work by Geoff Hammerson, the McElmo Natural Area and its immediate surroundings contain 13 species of snakes, lizards and amphibians, with at least another six species possible. This makes it one of the richest areas in the state for these animals. This fact alone would make the site significant. An added bonus is that several of the species are rare in Colorado, including the common kingsnake (Lampropeltis getula), the desert spiny lizard (Sceloporus magister) and the long-nosed leopard lizard (Gambelia wislizenii).
The common kingsnake is widespread through the U.S. In Colorado it is known only from the Four Corners area and parts of the lower Arkansas River drainage. The snake's skin has white bands or stripes on a black body. Adults are usually two feet long. The kingsnake is an aggressive predator, preying on rodents, birds, eggs and other reptiles, including lizards, rattlesnakes and bull snakes.
The desert spiny lizard is known in Colorado only from the Four Corners. Otherwise it occurs throughout northern Mexico and the southwestern U.S. This lizard prefers semi-arid shrublands or grassy plains near drainages. This diurnal lizard is very wary and will flee into hiding when threatened. It forages for insects, smaller lizards, and tender vegetation.
The longnose leopard lizard is also found throughout the western U.S. In Colorado, this large, distinctively patterned lizard is known only in the Four Corners and from the floor of the Grand Valley near Grand Junction. The leopard lizard’s natural habitat has sparse plant cover that offers plenty of running room. When fleeing predators, this lizard tucks its front legs against its body and runs upright. According to Geoff Hammerson, this species’ habitat has probably been significantly restricted in Colorado. This is due to conversion of its preferred valley floor habitats to agriculture or to dense stands of cheatgrass, which interferes with the animal’s movement.
The Bridge is Bridge Canyon’s other, and more conspicuous, natural feature. The Morrison Formation is a series of alternating hard sandstone and softer shale rock layers, into which Bridge Canyon is cut. One especially hard layer of sandstone resisted erosion as the valley deepened, and was left exposed as a "bridge" spanning the valley floor. The center of the bridge has collapsed, as have its downstream edges.
McElmo was brought to the CNAP’s attention early on and was one of the first sites considered for designation. It was registered in 1979 and designated in 1986. The site was on the BLM’s radar as early as 1964 thanks to the efforts of members of Fort Lewis College’s biology department, who had been taking students there for decades. It was recognized as a significant biological area by the International Biological Programs in 1970 and was designated as the McElmo Rare Lizard and Snake Research Natural Area by the BLM in 1973.
McElmo, despite its isolation, is far from pristine. Heavy sheep grazing prior to the establishment of the natural area converted much of the understory in the salt desert and greasewood shrublands from native bunchgrasses and desert forbs to cheatgrass. The area was fenced to exclude unauthorized domestic livestock in 1986 and the vegetation has recovered somewhat. A complete restoration of the native vegetation would require a concentrated investment of resources, although techniques to replace cheatgrass with native bunch grasses continue to advance. Without question, restoration of native vegetation on the floor of the canyon would improve the habitat for the many lizards and snakes of the McElmo Natural Area.
Reptiles and amphibians known to occur within the McElmo Natural Area:Tiger salamanderNew Mexico spadefoot toadRed-spotted toadWoodhouse’s toadCollared lizardLongnose leopard lizardSide-blotched lizardDesert spiny lizardNorthern plateau lizardTree lizardWestern whiptailBullsnakeWestern rattlesnake
Reptiles known to occur near the Natural Area and likely to occur there:Lesser earless lizardSagebrush lizardPlateau striped whiptailShort-horned lizardCommon kingsnakeStriped whipsnake