Large areas of the foothills and mesas in the southern and western parts of Colorado are covered by a mix of deciduous shrubs, including scrub oak, manzanita, serviceberry, mountain mahogany, skunkbrush, snowberry, and bitterbrush. These areas are usually found at elevations just above the pinyon-juniper habitats and just below the ponderosa pine forest, though they can intergrade with both those habitat types. The often-impenetrable montane shrubland thickets tend to be characterized by a relative lack of conifers, though Rocky Mountain juniper can be associated with them.
Montane shrubland thickets are the best places to find Virginia’s Warbler, Blue-gray Gnatcatcher, and Green-tailed Towhee. They can also support birds such as Black-headed Grosbeak, Spotted Towhee, and Western Bluebird. Large mammals including deer, elk, and black bear may feed here, and butterflies may include beauties like Black Swallowtail, California Tortoiseshell, and Coronis Fritillary. These habitats can put on quite a wildflower show in the right season, with the blooming of black-eyed susan, sulphur flower, yarrow, salsify, blue-eyed grass, stonecrop, and boulder raspberry, to name just a few.
Large parts of Colorado are covered with nearly pure stands of the native scrub oak, which rarely grows higher than 10 or 15 feet. No birds are restricted to this habitat, but it can produce foothill specialists like Western Scrub-Jay, Blue-gray Gnatcatcher, Lazuli Bunting, Spotted Towhee, and Virginia’s Warbler (the latter in areas with some ponderosa). Especially in the northwest part of the state, the oaks can be a good place to find Dusky Grouse displaying in spring. Colorado’s lovely and uncommon state insect, the Colorado Hairstreak, whose violet wing panels are bordered by black and orange, is restricted to this habitat.