Conservationists say livestock grazing poses a threat to a wide variety of fish and other wildlife across more than three-fourths of their dwindling habitats on federal land in the West.
Using satellite mapping and federal records, WildEarth Guardians began a study last year matching wildlife habitat and U.S. grazing allotments across more than 260 million acres of federal land in the West.
It includes practically all of the remaining habitat of the Greater sage grouse, a hen-sized game bird the U.S. Fish and Wildlife Service is considering adding to the list of threatened or endangered species in 11 Western states from California to Wyoming. The environmental group wants the bird protected.
"The results confirm - in graphic form - previous research finding that incessant, ubiquitous public lands grazing has contributed to the decline of native wildlife," concludes the report entitled "Western Wildlife Under Hoof." The report is scheduled to be released Friday.
The group said continued grazing in ever-shrinking habitat hampers the recovery of fish and wildlife and in some cases threatens them with extinction.
Cattle and sheep trample vegetation, damage soil, spread invasive weeds, spoil water and deprive native wildlife of forage, the report said. It notes that then-Interior Secretary Bruce Babbitt said in 2005 that livestock grazing "is the most damaging use of public land."
Mark Salvo, WildEarth Guardians' grazing program specialist and author of the report, said the new data suggest livestock have "done more damage to the Earth than the chain saw and bulldozer combined."
Jeff Eisenberg, director of federal lands for the National Cattlemen's Beef Association, criticized the findings as part of an effort to shut down grazing on federal lands.
"There's a number of environmental groups that have decided the best way to spend their time and the money of their funders is to eliminate the families and communities that have made the West what it is today," he told AP in an e-mail. "These groups don't deserve a dignified response."
Don Kirby, president of the Society for Range Management and director of North Dakota State University's School of Natural Resource Sciences, said livestock grazing is an important part of a "landscape management toolbox" that can be used to reduce wildfires and improve wildlife habitat.
"Western rangelands and the wildlife species that live there have coexisted with grazing by large herbivores for tens of thousands of years," Kirby said.
The report found livestock grazing is permitted on 91 percent of the Greater sage grouse's habitat and that grazing operations are active on 72 percent of the habitat. Grazing is active on 55 percent of the federal range of the Gunnison sage grouse and is permitted on 84 percent of it.
Likewise, grazing is permitted on about 80 percent of public land in the historic range of several cutthroat trout species, including 88 percent of the Lahontan and 76 percent of the Bonneville.
It's also permitted on about 75 percent of the federal habitat of four species of prairie dogs.
"The species included in our report are representative of the hundreds of wildlife species that are threatened by public lands grazing," said Salvo, whose group has offices in Colorado, New Mexico and Arizona.
The bulk of the federal land studied is managed by the Bureau of Land Management, which issued grazing permits and leases to 15,799 ranchers and other operators covering 128 million acres of U.S. land in 2006.
BLM spokesman Jeff Krauss said the agency has not fully reviewed the report but maintains "well-managed grazing provides numerous ecological and environmental benefits."
Among other things, WildEarth Guardians recommends buying out permits from ranchers and others willing to remove their livestock from grazing land.
"There is a greater economic value in non-consumptive uses of public land - hunting, fishing, birdwatching, hiking, camping - than livestock grazing," the report said.
The Nevada Department of Wildlife shares concerns about dwindling wildlife populations but believes there is a place for grazing on public land, spokesman Chris Healy said.
If ranchers end up selling their land, it could be subdivided and lead to development even more problematic for wildlife, he said.
"It behooves us to get everybody who uses the land to be part of the solution and that's what we've been trying to do with the sage grouse. If one sector or user of the land feels like they are being ganged up on, the odds of coming up with a solution that will work are not good," he said.