"We're concerned that the pronghorn population will be reduced because of the development and that we'll lose this long-distance migration," says Joel Berger, a senior biologist for the Wildlife Conservation Society in Driggs, Idaho.

No creature has been as impacted by this activity as the sage grouse, a flamboyant, ostentatiously plumed bird the size of a chicken. In an elaborate courtship ritual that takes place on the plains each spring, males thrum and strut about as adoring females look on—and bird-watchers and naturalists make pilgrimages to blinds to see the spectacle unfold.

Recently published research has found that in areas developed for methane production, the birds are likely to disappear within four years on average. From 2000 to 2005, sage grouse populations within coal bed methane fields in Wyoming declined by 86 percent. Mule deer numbers are down on energy-producing land as well.

Hunters, guides, and environmentalists in western Wyoming, meanwhile, are fighting to prevent similar problems from occurring in the Wyoming Range, a rugged region of snow-mottled peaks and broad valleys. Widespread leasing for natural gas in areas that provide habitat for bear, moose, elk, and deer has provoked a huge outcry from people like Gary Amerine, a hunting outfitter in Daniel, Wyoming, who heads a group called Citizens Protecting the Wyoming Range. "Where is it going to stop?" he asks. "Does everything become an energy development area? Are people going to lose the places they fish and hunt? Forest Service land is designated for multiple use, but oil and gas makes it single use."

As colossal as the problem already seems, there are many more plans on the drawing board. The Department of the Interior recently completed an environmental-impact study of commercial oil-shale and oil-sands production in Colorado, Utah, and Wyoming—processes that are especially destructive. It will release its findings in December 2007. One of the places under consideration is the red rock country of the spectacular Grand Staircase–Escalante, which was designated a national monument during the Clinton administration.

There are also coal-fired power plant proposals around the West. Five of the proposals are in Nevada and Utah, and ten are in Wyoming. In Montana, the federal government is funding a coal-fired power plant next to the National Historic Site where Lewis and Clark camped and portaged around the Missouri River. A mammoth coal-fired power plant called Desert Rock is proposed by the Navajo tribe in New Mexico; the plan has garnered widespread opposition from environmentalists, some Navajos, and New Mexico governor and presidential candidate Bill Richardson. "The vistas in the Southwest have eroded significantly," says David Nimkin, regional director of the National Parks and Conservation Association. "If you add additional coal-fired power plants, it will make it even worse." (See "Too Close for Comfort," for the parks and monuments most affected.)