Semidesert Shrubland is another broad category that includes a number of distinct plant associations in Colorado. It is found mostly at lower elevations on both slopes, as well as in the flat bottoms of the intermountain parks, the San Luis Valley, and the Gunnison basin.
The most widespread type of semidesert shrubland is the sagebrush steppe. Sagebrush is the collective name for a number of similar shrubs which are recognizable by the distinctive blue-green coloration of their tiny leaves. Sagebrush dominates the lower, drier elevations of the state, particularly on the West Slope and in the mountain parks. It can be quite short (rarely higher than a foot in the mountain parks, for instance), or quite large (with individual giant plants up to eight feet tall in parts of southwest Colorado). Birds that breed mostly in sagebrush in Colorado include Greater and Gunnison Sage-Grouse, Sage Thrasher, and Brewer’s, Black-throated and Sage Sparrows. Other birds that can often be found in areas of sage include Western Kingbird, Loggerhead Shrike, Horned Lark, Western Meadowlark, and Brewer’s Blackbird. This habitat can be excellent for butterflies also, producing species such as Variable, Sagebrush, and Edith’s Checkerspots, Edith’s and Blue Coppers, Bramble Hairstreak, and Callippe Fritillary.
Greasewood and saltbush, which are superficially similar but unrelated to sagebrush and to each other, also blanket large areas of the state. They are particularly common in the San Luis Valley, where there is relatively little sagebrush. There they support Sage Thrasher and Brewer’s and Sage Sparrows, in addition to other common birds of the shrub-steppe environment. In many places, flowering rabbitbrush can turn the semidesert steppe into a sea of yellow in spring and summer.
Cholla cactus (pronounced “choya”) is typical of semidesert shrublands in the southeastern part of Colorado. It is the cactus you least want to come into physical contact with. Sometimes growing up to 5 feet tall, these treelike plants are armed with some truly evil spines. That’s probably why Scaled Quail and Curve-billed Thrasher like them so much! Among the cholla, look also for roadrunners, rattlesnakes, short-horned lizards, tarantulas, and other creatures often associated with the southwestern deserts.
Wildlife of the Semidesert Shrubland
The Gunnison Sage-Grouse is a spectacular but declining bird of the western sagebrush. It is restricted to seven isolated locations in Colorado and one tiny population in Utah. In early 2013, the U.S. Fish and Wildlife Service placed it under consideration for listing under the Endangered Species Act. The males have an extravagant spring display in which they puff out their bodies, fan their tails into a starburst, and make low, gurgling sounds with bizarre froglike air sacs in their chests—watch an awesome video from Cornell Lab of Ornithology.