The U.S. Forest Service has built its first corral for wild horses, which could allow it to bypass federal restrictions and sell the animals for slaughter. The agency acknowledged in court filings in a potentially precedent-setting legal battle that it built the new pen in Northern California for mustangs gathered this fall on national forest land along the Nevada border because of restrictions on such sales at other federal holding facilities.The agency denies claims by horse advocates it has made up its mind to sell the more than 250 horses for slaughter. But it also says it may have no choice because of the high cost of housing the animals and continued ecological impacts it claims overpopulated herds are having on federal rangeland."While slaughtering wild horses does not present a pleasant picture, the reality of this dire situation is not pleasant," Justice Department lawyers representing the agency wrote in its most recent filing last month. "The Forest Service is taking a step to reduce what is universally recognized as a natural catastrophe."