page_title: Ecology of the Rocky Mountains
section_title: Beaver
hierarchical_section_title: Ecology of the Rocky Mountains / Fauna / Mammals / Beaver
caption_attribution_description: Tamias minimus (Least Chipmunk), Glacier National Park, USA
context_page_description: The ecology of the Rocky Mountains is diverse due to the effects of a variety of environmental factors. The Rocky Mountains are the major mountain range in western North America, running from the far north of British Columbia in Canada to New Mexico in the southwestern United States, climbing from the Great Plains at or below 1,800 feet to peaks of over 14,000 feet. Temperature and rainfall varies greatly also and thus the Rockies are home to a mixture of habitats including the alpine, subalpine and boreal habitats of the Northern Rocky Mountains in British Columbia and Alberta, the coniferous forests of Montana and Idaho, the wetlands and prairie where the Rockies meet the plains, a different mix of conifers on the Yellowstone Plateau in Wyoming and in the high Rockies of Colorado and New Mexico, and finally the alpine tundra of the highest elevations.
context_section_description: Beavers once played important roles in shaping vegetation patterns in riparian and meadow communities in the Rocky Mountains. Studies of beaver populations in one small area in Yellowstone National Park (Tower Junction area) in the early 1920s reported 232 beavers and extensive beaver dams. Repeated surveys in the same area in the early 1950s and in 1986 revealed no beavers or dams. Beavers need aspens or tall willows for food and building materials—resources that are made scarce by lack of both fires and floods and by herbivory by elk, moose, and domestic livestock. Beaver ponds are known to maintain fish and invertebrate populations and to create and maintain riparian zones that are critical to wildlife, yet the beaver is virtually absent in many areas. By 2015, Yellowstone had an estimated 100 colonies. Causes for their increase include predation of elk by wolves, which allowed aspens and willows to grow taller.
caption: A least chipmunk in Glacier National Park
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