Choteau, Montana, USA Photograph by David Olson   Central North America: Southern central Canada into northern United States Temperate Grasslands, Savannas, and Shrublands   31,500 square miles (81,700 square kilometers) -- slightly larger than Maine Critical/Endangered

· Grizzly Bears and Bighorn Sheep
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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Grizzly Bears and Bighorn Sheep

When explorers Lewis and Clark crossed the high valleys and foothills of this ecoregion in the central Rocky Mountains in 1805 and 1806, they walked among teeming herds of bison, elk, and bighorn sheep. Today's traveler sees considerably fewer of these ungulates (hoofed mammals), but wildlife still abounds. And on a lucky day of hiking, one may hear the bellow of a bull elk or catch a glimpse of a grizzly bear.

Special Features

Located in what is called the Chinook "wind belt," a region where warm winds moderate temperatures, this area enjoys dry, warm summers and mild winters. The fingers of these grasslands stretch from the high-elevation mountain valleys down along the banks of the river basins and wetlands and across the flatlands of the foothills. Plants range from fescues and wheatgrasses to fragrant sagebrush. The Centennial Valley of southwestern Montana supports 487 vascular plant families and large breeding populations of sandhill cranes and trumpeter swans. Highly productive wetlands and grasslands in the Valley separate different mountain grizzly populations, and possible recolonization sites for grizzlies are in the lowland area. This valley and other undeveloped valleys provide critical linkage habitats for grizzlies and other animals moving between separate mountain ranges.

	Around 100 million years ago, a tropical moist forest covered these plains. The birth of the Rocky Mountains 60 to 80 million years ago slowly carried the humid forests to higher, colder elevations, and the tropical trees were eventually replaced by the dry grasses that cover the river valleys today.

Wild Side

Grizzly bears descend from the adjoining Rockies to forage in the grasslands and along the rivers. White-tailed deer, pronghorn antelopes, grouse, and ground squirrels also find habitat in the valleys and foothills. The prairie potholes (depressions left by ancient glaciers) and the many lakes and rivers provide refuges for birds, such as trumpeter swans, great blue herons, and sandhill cranes.

Cause for Concern

The cities of Montana and Alberta are expanding into this ecosystem, cutting off travel routes and winter ranges for elk, mule deer, and other animals. New housing developments also introduce exotic plant species that spread and drive out the native grasses and shrubs. Additional threats include large-scale agriculture, pollution from mining, and toxic waste sites.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.