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,
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