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ridge tops and talus slopes. Big sagebrush (Artemisia tridentata) dominates this plant <br />community. Other shrubs present include saltbush (Atriplex canescens), shadscale (Atriplex <br />confertifolia), rabbitbrush (Chrysothamnus nausoesus), mountain mahogany (Cercocarpus <br />montanus), bitterbrush (Purshia tridentata), winterfat (Eurotia lanata), and, where soils are <br />more saline, greasewood (Sarcobatus vermiculatus). Prickly pear (Opuntia sp.) is common. <br />Among the grasses found here are cheat (Bromus tectorum), western wheat (Agropyron <br />smithii), bluebunch wheat (Agropryon spicatum), needle-and-thread (Stipa comata), Indian <br />ricegrass (Oryzopsis hymenoides, and junegrass (Koeleria cristata) (U.S.D.A. SCS 1982). <br />Greasewood is common in the lower drainage bottoms, as well. <br />Stands of pinyon and juniper occur on the ridges and talus slopes throughout the <br />study area. Juniper (Juniperus utahensis) is the dominant species, occurring both in pure <br />stands and with scattered pinyon (Pinus edulis). Within such woodlands there is very little <br />understory, although any of the plants associated with the sage shrubland community <br />(described above) can be found here as well. <br />Fauna <br />Numerous wildlife species inhabit the study area. Studies by Baker and McKean <br />(1971: 7-16) and Cringan (1973) suggest that there are at least 340 species in the Piceance <br />Basin; among them 83 are mammals, seven of which the Colorado Division of Wildlife <br />classifies as big game, four as small game, and nine as fur-bearers (Grady 1980: 53). <br />An important mammal in the basin today (and presumably in the past) is the mule <br />deer (Odocoileus hemionus) whose winter population density in the Yellow Creek/Piceance <br />Creek area is estimated at 52 per square mile (Baker and McKean 1971: 22). During the <br />summer months, the deer herds migrate to the higher elevations of the basin, generally <br />above 7500 feet (Grady 1980: 53). <br />Other mammals found locally include feral horses, mountain cottontail (Sylvilagus <br />nuttalli), white-tailed jackrabbit (Lepus townsendi), bushytail woodrat (Neotoma cinerea), <br />deer mouse (Peromyscus maniculatus), Colorado chipmunk (Eutamius quadrivittatus), <br />golden-mantled squirrel (Citellus lateralis), rock squirrel (Citellus variegatus), bobcat (Lynx <br />rufus), coyote (Canis latrans), red fox (Vulpes fulva), badger (Taxidea taxus), and skunk <br />(Mephitis mephitis). Bird species observed in the Piceance Basin include the jay, horned <br />lark, raven, red-shafted flicker, long-eared owl, golden eagle, and various other raptors. <br />Goose, duck, grouse, pheasant, and dove are reported in the basin as well (Baker and <br />McKean 1971; Cringan 1973; Jennings 1975). <br />Climate and Land Use <br />Climatically, the region is characterized as having a cool, semiarid, steppe-type <br />climate. Average annual rainfall ranges between 12 and 16 inches. Temperatures have <br />varied between -20 degrees Fahrenheit in winter and 90 degrees Fahrenheit in summer with <br />a frost free seasonal range of 70-to-100 days. Agriculture is limited by the low rainfall, <br />7