Places We Protect

Bighorn Basin


Dramatic reddish cliffs rising up from open rolling rangeland.
Wyoming Bighorn Mountains The land as it rises up to Tensleep Preserve from the Bighorn Basin. © Edward Orth



Few mountain ranges in the West span a wider variety of landforms and ecosystems than the Bighorns. Shortgrass prairie and sagebrush lap its eastern slopes, while on its western side naked badlands descend into cottonwood stands along the Bighorn River. The Bighorns’ steep flanks are carved by streams, leaving spectacular chasms—the canyons of Shell Creek, Tensleep Creek, Crazy Woman Creek and a dozen others.

The Bighorns’ biodiversity long has appealed to humans. For thousands of years, Native Americans found good hunting here, and settlers later discovered agricultural promise. The area’s many large ranches provide both space and natural qualities that visitors and residents treasure.

The Bighorns are also distinct from other Wyoming mountain ranges in terms of geology, housing the most extensive area of exposed limestone in the state, providing habitat for many rare plant and animal species.


Rare and threatened plants grow here, including a violet-blue flower called Cary's penstemon. It grows better on the Conservancy’s Tensleep Preserve than almost anywhere else. Northern Arnica, Soft Aster, Williams' Waterparsnip, Mountain Lady's Slipper, Giant Helleborine, Hall's Fescue, Marsh Muhly, Northern Blackberry and Hapeman's Sullivantia are other rare grasses, plants and wildflowers.


This land is named for the Bighorn sheep that once numbered a million. Their population has plummeted by more than 92 percent. Large herds of deer and elk now live here, along with moose, waterfowl and upland game birds, but even they face growing threats from development and destructive land management. Bear and mountain lion are prevalent as well.

Because the Bighorns are isolated from other mountain regions, much of the wildlife found here is genetically unique. Montane vole, American pika, snowshoe hare and least chipmunks are genetically distinct from the Wind River, Absaroka or Black Hills species by the same name. Even the black bear on the Big Horns are only distantly related to black bears on the Tetons and Snowy Ranges.

Why the Conservancy Selected this Site

The rugged beauty, abundant wildlife and friendly western culture of the Bighorns makes it an increasingly popular destination—to live and visit. Because of this, the Bighorn Mountains face increasing pressures from population. Large tracts of ranch land have become housing subdivisions, threatening the very qualities that people most savor. With housing and road development come fragmented habitat, disturbed plant communities, blocked wildlife migration corridors and suppressed natural fire processes. These crucial elements of a healthy, functioning ecosystem must be conserved if the Bighorns are to retain their essential character.

What the Conservancy Has Done/Is Doing

The Conservancy is working in partnership with local ranchers and conservation-minded citizens to preserve large pieces of land for future generations. One of the most powerful, effective tools available for the permanent conservation of private lands is conservation easements. Their use has successfully protected thousands of acres of wildlife habitat and open space in the Bighorns, keeping it in private hands and generating significant public benefits.

The Conservancy’s Tensleep Preserve protects a critical 9,000 acres of the mountain’s southwestern flank. It also features a lodge and special programs.


Limited Access


North-central WY and south-central MT

Map with marker: Map with location of Bighorn Mountains


5,353,790 acres: 4,116,119 acres in Wyoming and 1,237,671 acres in Montana

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