Description and Ecology: Lowland riparian forests border streams as they flow out of the foothills onto the eastern plains. Plains cottonwoods interspersed with thickets of willows and other shrubs such as wild plums, hackberries, hawthorns, chokecherries, and box elder generally line these streams in eastern Colorado. Many of these lowland riparian areas have been substantially altered by humans to create residential, industrial, and recreational developments and to create highways and gravel mines.

Various sources report that riparian forests comprise less than 3% of the total landscape, but up to 80% of the resident bird species use them for some part of their life cycle. Birds use this habitat for nesting, cover, resting, migration stopover areas, and migration corridors. This system has the richest avian species component of any of Colorado's habitats. Common species in lowland riparian forests in Physiographic Area 36 include American Kestrel, Eastern and Western Screech-Owls, Great Horned Owl, Mourning Dove, Northern Flicker, Western Wood-Pewee, Western Kingbird, Eastern Kingbird, House Wren, Black-billed Magpie, American Robin, Yellow Warbler, Blue Grosbeak, and Bullock's Oriole (Andrews and Righter 1992, Krueper 1995, Howe 1996, Kingery 1998).

Importance and Conservation Status: Lowland riparian systems provide dispersal corridors for woodland birds across otherwise treeless terrain. Well-defined, unique, and highly productive, riparian areas are sensitive to disturbance (Melton et al. 1984).

Riparian ecosystems are important for both humans and wildlife. During historic times, humans have used riparian zones intensively and have substantially altered much of this habitat to create highways, gravel mines, and residential, industrial, and recreational developments. Riparian zones are convenient locations for those activities. They are also productive areas for domestic livestock grazing. However, the impacts of domestic livestock are not as dominant as in high elevation riparian zones (Melton et al. 1984, Wozniak 1995).

Unlike the high elevation riparian habitat in Colorado, much of the lowland riparian ecosystem is in private ownership; consequently, it is much more susceptible to loss and degradation by urban and industrial development, mining, road and trail development, and recreational development.

Priority Species Accounts: Two species are identified as high priority in lowland riparian habitat in Physiographic Area 36: Lewis's Woodpecker and Bell's Vireo.