Physiographic Area 87 includes into two subregions--the Colorado Plateau and the Basin and Range country of central New Mexico. The Colorado Plateau is a high, flat tableland carved into soaring mesas, great cliffs, chasms, and canyons. It includes much of northern Arizona, eastern Utah, western Colorado, and northwestern New Mexico. The entire length of the Colorado-Utah state line lies within the region, and in Colorado the region extends upstream along the lower basins of the Yampa, White, Colorado, Gunnison, Dolores, and San Juan rivers to the Southern Rocky Mountain region to the east and the Wyoming Basin to the north. The Basin and Range region borders the Colorado Plateau at the continental divide in northwestern New Mexico and takes in much of central New Mexico, extending northward into Colorado to include Raton Mesa, Mesa de Maya, and the San Luis Valley. The Colorado portion of the Basin and Range region is included in the Colorado Plateau in this plan, although New Mexico Partners in Flight distinguishes the two subregions. The Colorado Plateau Coalition delineates other boundaries excluding most of northwestern Colorado and the Uncompahgre Plateau.

In Colorado, elevations of the mesa tops range from 1500 to 2800 m (4,921-9,186 ft) and some mountain peaks reach as high as 3840 m (12,598 ft). In many areas, local relief is greater than 900 m (2,953 ft). The area takes in 34,213 km² (13,210 mi² ) of Colorado.

Within Colorado, the Colorado Plateau contains a high proportion of publicly owned lands. The Bureau of Land Management is the area's largest landowner. The National Park Service maintains a national park and five national monuments in western Colorado. The parks and monuments are devoted to geologic phenomena, especially canyons, and to the archeological remains of ancient cultures. Most of the highest elevations fall within the domain of the U.S. Forest Service, and three national forests lie partially within the region. The Southern Ute Indian Reservation lies along the New Mexico-Colorado border. The largest portion of private lands in Physiographic Area 87 are farm and ranch lands. These, along with the area's rather limited urban developments, are primarily located along the lowland riparian zones.

Historically, the most extensive land use in the Colorado Plateau has been livestock grazing, and most of the public as well as private land is currently grazed. There has also been extensive mineral, oil, and gas development. Aspen, ponderosa pine, and spruce-fir forests at higher elevations are logged. The region is popular for outdoor recreation, and many miles of primitive roads and trails support extensive off-road vehicle use.

The tablelands that give the physiographic area its name also host its most significant vegetative habitats: pinyon-juniper and sagebrush. In the northern part of the physiographic area in Colorado, sagebrush covers broad areas and is the most expansive habitat. Pinyon-juniper woodlands are scattered through the sagebrush in northwestern Colorado, and moving south pinyon-juniper becomes more and more extensive and sagebrush becomes less so. Pinyon-juniper covers most of the lower slopes in western Colorado and the mesas of southeastern Colorado and is the most representative habitat of Physiographic Area 87.

Semidesert grasslands, often intermixed or replaced by introduced annuals, especially cheatgrass, cover large expanses at the broad low valleys of the physiographic area in Colorado. This habitat is typically the result of wildfires killing the shrubs. Desert shrubs, especially greasewood and four or five saltbush species, often grow in open stands among the grasses.

Although they are widely scattered in this dry area, wetlands support dense bird populations. Many of Colorado's largest and richest ponds, lakes, and marshes lie in the San Luis Valley. In lowland riparian, Fremont cottonwood and a variety of other trees and shrubs, including skunkbrush and box elder, support a large number of birds. In addition, a number of bird species rely on the shores and banks of the lowland streams and rivers. Several exotic plants, notably salt cedar, Russian-olive, and Russian knapweed have extensively invaded lowland riparian areas in the last century. Irrigated agriculture has also extensively invaded the lowland riparian areas, with the effect of broadening the riparian zone, while degrading the original riparian areas. The rivers of the Colorado Plateau have carved numerous deep canyons in the tableland, and cliff/rock habitats may be more significant here than in any other Colorado region.

On the higher plateaus, mesas, and mountains a wide variety of less extensive habitats are found. Just above the pinyon-juniper zone, and often intermixed with that vegetative type, Gambel oak, mountain mahogany, serviceberry, and other mountain shrubs dominate.

On the flanks of higher plateaus, ponderosa pine is found, often mixed with aspen. Gambel oak frequently forms an important understory. Large stands of aspen that appear not to be successional are found in western Colorado. At similar elevations, mixed conifer stands, especially Douglas-fir, tend to dominate on steep north-facing slopes and in other situations of greater moisture and cooler temperatures.

Along streams in the mountainous areas, narrowleaf cottonwoods stand above a wide variety of shrubs in the narrow riparian zones, which, although limited in extent, support an extraordinarily rich avifauna. The cottonwoods in this zone often are intermixed with or replaced by blue spruce and Douglas-fir at higher elevations.

Spruce-fir forests cover the highest plateaus and mountain tops in the area.

Conservation Issues

Livestock grazing is the most extensive use of land in western Colorado, and the extent and timing of grazing are constant conservation issues. The manipulation of habitats (e.g., sagebrush and pinyon-juniper "treatment") for improved grazing and the degradation of habitats (especially riparian) by grazing have significant effects on wildlife. Livestock water development and operation offers hazards and opportunities for wildlife. It should be kept in mind that the prevailing opinion in the industry is that public rangelands have improved since 1934, the year of the Taylor Grazing Act, the law that put order onto the public grazing land and incentives for ranchers to improve the range.

The manipulation of water, including irrigation and dam building, and the resultant land uses (orchards, farms, industrial, residential) have created major threats to wildlife habitats, especially the lowland riparian where water storage and allocation has greatly reduced cottonwood regeneration and has encouraged exotic plant invasion (e.g., salt cedar, Russian knapweed). Irrigation has also expanded waterbird habitat in the arable valleys. New threats continue to emerge: a ballot issue on quantifying water use in the San Luis Valley was recently defeated, primarily over the concern that surpluses might be identified, declared, or trumped-up and diverted outside the upper Rio Grande River system. If this concern were to become fact, significant impacts to bird life could occur not only in Colorado, but also in New Mexico and the lower Rio Grande Valley, which is nationally significant.

The control of natural fires has created successional patterns that may be quite different from historical patterns and which may have profound effects on wildlife populations and distribution. Pinyon-juniper has expanded. Fire exclusion has resulted in stands overstocked with small trees. Wildfires tend to be less frequent and more catastrophic. The result has probably been harmful to non-forest raptors and seed-eaters, and has been beneficial mostly to non-game upland bird species.

The widespread recreational use of lands in western Colorado also creates several conservation issues, including wilderness designation, off-road vehicle use, and trail proliferation.

Conservation Opportunities

The incipient BLM fire management planning process, with PIF participation, will consider practices which would maintain or enhance bird habitat.

Several cities and counties (Delta, Montrose, Naturita, DeBeque, Parachute, Rifle-Silt, Rangely, Durango, Alamosa, towns of the Grand Valley) in the region have initiated riverfront improvement projects and may be responsive to guidance on restoring degraded lowland riparian habitats.

The many units of the National Park System on the Colorado Plateau create numerous public information opportunities.

Widespread public concern about wildlife could make a illustrated guide to wildlife (bird) hazards (e.g., power lines, fences, antenna towers, buildings, petroleum waste pits, road settings, feral animals, etc.) effective in reducing those hazards.

Public debate on water issues (e.g., Animas-LaPlata) could highlight lowland riparian conservation issues.

The Endangered Fishes Program of the USFWS and CDOW, by increasing spring flows and creating backwaters, may have significant implications to birds.

Travel use planning could incorporate bird considerations (e.g., keeping distance from nesting raptors).

The Colorado Plateau Coalition in Moab could be an effective agent in promoting bird conservation.

Ranchers and wildlife habitat developers have yet to find effective guidance on developing watering sites. An example of this is that a simple and effective wildlife ramp for a circular water tank has yet to be designed and published widely.

Avifaunal Analysis

Physiographic Area 87 hosts at least 190 species of breeding birds in the eight habitats that will be discussed below. This area has few species that are wholly or nearly absent from other regions of the state; Gambel's Quail, Black-throated Sparrow, Sage Sparrow, and Scott's Oriole fit this group. More species reach their best numbers in this physiographic area; Chukar, Western Screech-Owl, Canyon Wren, Brewer's Sparrow, and several pinyon-juniper woodland species are in this class. Curiously, nesting Purple Martins cluster along the boundary between the Colorado Plateau and the Southern Rocky Mountain physiographic areas.