Places We Protect

Thunder Basin


View across a dry grassland toward a red butte under a blue sky with patchy clouds.
Thunder Basin Wide open space at Thunder Basin in Wyoming. © Amy Pocewicz

Thunder Basin contains a vast expanse of intact native prairie.

TNC is part of one of the largest voluntary conservation agreements in recent history. We joined with a broad coalition of partners to finalize a conservation strategy that reaches across more than 13 million acres of the Thunder Basin and northward into Montana.

The agreement protects several species of concern—including burrowing owls, Ferruginous hawks, and greater sage-grouse—by avoiding fragmentation or destruction of vital habitat.

Under the agreement, landowners—including livestock producers and energy companies—implement voluntary conservation actions which help wildlife that were headed toward becoming candidates for threatened or endangered species listing. A key partner in the coalition is the Thunder Basin Grassland Prairie Ecosystem Association (TBGPEA).

A Wide Open Land

Thunder Basin tests our tolerance for wide-open spaces. People who don’t live here struggle to comprehend the apparent endlessness of a horizon rolling away into a vast, swallowing sea of open sky.

The Thunder Basin’s high, relatively cold climate has made its rich soil unattractive to the furrowing plows that overturned much of America’s Great Plains. As a result, these grasslands contain some of the most intact native prairie left in the U.S.

With time, impacts on Thunder Basin’s grasslands will continue to mount. Much has already changed since the first European explorers waded through the prairie. Bison that once dominated this landscape are long gone, and many grassland species face an uncertain future.


The Thunder Basin grasslands are mixed-grass prairies, where fifty or more plant species may thrive in a two-acre area. These grasses are drought-tolerant and many are well-adapted to large grazing mammals. Lightning-sparked wildfires are what help many grass species germinate and reproduce. In some areas, grasslands give way to sagebrush, cactus, or woodlands with Ponderosa pine, limber pine, or juniper.


Life recycled in grassland soils provides nutrients to a wide diversity of animals. Ferruginous hawks, swift foxes, pronghorn and black-tailed prairie dogs all inhabit the Thunder Basin. The black-tailed prairie dog is particularly important for its role building burrows and cropping vegetation that creates habitats for other species. Many grassland birds migrate from as far away as Mexico and South America to spend part of each year in the Thunder Basin, including the burrowing owl, mountain plover and Sprague’s pipit.

Why TNC Selected this Site

Grasslands are the least protected habitat on Earth. Fragmentation caused by residential development, invasion by non-native plants, coal and coal-bed methane mining, and altered natural fire patterns have all taken a toll. Fortunately, the Thunder Basin still contains a vast expanse of intact native prairie—due in part to the stewardship of landowners. As a result, the Conservancy and its partners have a chance to protect these grasslands now, while they still exist across their historic range.

TNC's Strategy

In the Thunder Basin grasslands, federal and state lands intermingle with vast expanses of private lands ownership, even one of the largest coal companies in the U.S. Cooperative efforts that bring farmers, ranchers, and other landowners to the table are the only way we can help continue a tradition of conserving Wyoming’s native grasslands. By combining our efforts with coalitions such as the Thunder Basin Grasslands Prairie Ecosystem Association, the Conservancy is exploring solutions that address human needs as well as conservation priorities.


Trey Davis, Eastern Wyoming Stewardship Director
Phone: 307-366-2671

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