Including Ecosystem Characteristics and Features
The presence of springs in the Organ Mountains makes the area critically important to wildlife including golden eagles, hawks, owls, mule deer, Montezuma quail, and mountain lions. Desert bighorn sheep were historical inhabitants and could be reintroduced. Special-status animal species occurring in the Organs are the peregrine falcon, an Organ Mountain species of the Colorado chipmunk, and four species of endemic mollusks. Rare plants found here include Agastache cana, grayish-white giant hyssop, Draba stanleyi, Standley’s whitlow grass, Escobaria organensis, Organ Mountain pincushion cactus, Hymenoxys vaseyi, Vasey’s bitterweed, and Salvia summa, supreme sage. Five endemic plants species are found in the Organs: Agastache pringlei var. verticillata, Organ Mountain giant hyssop, Castilleja organum, Organ Mountain paintbrush, Oenothera organensis, Organ Mountain evening primrose, Perityle cernua, nodding cliff daisy, and Scrophularia laevis, Smooth figwort. Additional rare plants that likely occur in the area include Escobaria sneedii var. sneedii, Sneed’s pincushion cactus, Peniocereus greggii var. greggii, night-blooming cereus, Hexalectris spicata var. arizonica, Arizona coralroot, and Silene plankii, Plank’s campion. The diverse plant life also includes black grama grasslands; mixed cactus and desert shrubs; montane shrublands with sumac, mountain mahogany, and Wright’s silktassel; oak, pinyon, and juniper woodlands; and small pockets of ponderosa pine forest.
The diversity of vegetation types found in the Sierra de las Uvas Mountains Complex is exceptional. Juniper woodland, juniper savannah, and montane shrubs such as mountain mahogany, shrub live oak, and sumac are found in the higher elevations; desert shrub-cactus associations with plants like creosote, ocotillo, sotol, yucca, barrel cactus, penstemon, and lyreleaf greensages in the lower elevations; large areas of black grama grasslands on the mesas of the Sierra de las Uvas; expansive tobosa grass swales in some areas of the desert flats; arroyo riparian areas with plants like velvet ash, netleaf hackberry, soapberry, desert willow, wolf berry, sumac, and sacaton grass in the larger canyons of the area. The lush riparian zone along the Rio Grande is also adjacent to the complex. The Robledo Mountains support an unusually high diversity of cacti, including the State-endangered night-blooming cereus.
Pronghorn, mule deer, mountain lion, bobcat, coyote, bats, rock squirrels and other rodents, quail, and numerous other birds call this area home. The grasslands found here are important to a declining grassland fauna and provide habitat for rare birds like the Aplomado falcon and Baird’s sparrow. The abundance of cliffs in the mountains provides nesting and perching sites for many raptors, including bald and golden eagles, various hawks and owls, and the Federal-endangered peregrine falcon. Reptile diversity is also high; banded rock rattlers, Madrean alligator lizards, and Trans-Pecos rat snakes are all found here, as are other reptiles that reach the northern or western limits of their range.
The Sierra de las Uvas Mountains Complex also contains important watershed values since canyons in the northern and eastern parts of the area direct rainfall to the Rio Grande. These canyons are also important corridors for the movement of animals from the desert areas to water sources along the river.
Chihuahuan Desert grassland and yucca, in association with a mosaic of other desert shrubs such as creosote, acacia, and mesquite, make up the majority of the plant cover in the Greater Potrillo Mountains. Isolated clumps of netleaf hackberry and other desert trees are found in the lava flow where depressions or deeper pockets of soil hold extra water after rainfall. Occasional juniper trees are also found on mountain slopes and in larger drainages. The limestone substrate of the East Potrillo Mountains provides habitat for a wide diversity of cacti, and sandy areas likely contain populations of the State-endangered sand prickley pear, Opuntia arenaria, a BLM special status species. The late summer rains bring extensive stands of wildflowers in this area including white and yellow desert zinnias, desert marigolds, blackfoot daisies, globe mallow, pepperweed, desert sunflowers, Chihuahuan flax, and summer poppy. In one of the large basins in the center of the West Potrillo Mountains, there is a unique ‘cholla savannah’ vegetation type with large 8 to 10 foot tall cholla trees evenly spaced amongst the grasses. Unusually large specimens of barrel cactus are also found in this area.
Protection of large natural areas is particularly important for long-term preservation of biological diversity. Each unit is an important component in the larger complex of wildlands in the Greater Potrillo Mountains area. This area’s proximity to northern Mexico adds to its ecological significance. The Greater Potrillo Mountains Complex forms a biotic link between species in northern Mexico and those in the southwestern United States. The area’s naturalness and large size also contributes to its significance for wildlife. Raptors are common, especially during the winter. Golden eagles, great-horned owls, and Swainson’s hawks nest here, and peregrine falcons have also been reported. Extensive grasslands in the area provide important habitat for grassland birds that have declined in recent years. This includes potential habitat for Aplomado falcons. Other species that forage and live in the area include pronghorn, mule deer, quail, jackrabbits, and occasional migrating ducks on ephemeral ponds. A high diversity of bats are found in the complex, and melanistic forms of mammals and reptiles occur on the lava flows. The Great Plains narrow-mouth toad has been reported immediately to the south of the West Potrillo Mountains and can be expected to occur here. A rare mollusk is also found in the area.