The isolation of the Sierra del Carmen and its relatively undisturbed environment has led to conservation efforts in Mexico and jointly with the United States. Much of the Sierra del Carmen has been declared by the government of Mexico the Maderas del Carmen Flora and FaunaProtected Area, a designation which allows many economic activities and private land holdings to continue to exist within the boundaries. The protected area comprises 520,000 acres The Maderas del Carmen is part of a bi-lateral conservation project called the El Carmen—Big Bend Conservation Corridor Initiative which includes contiguous land designated for conservation on both sides of the border totaling more than 3 million acres, an area almost as large as the U.S. state of Connecticut. In 2005, Maderas del Carmen became the first designated Wilderness area in Latin America. The Maderas del Carmen Protected Area was created in 1994, although conservation efforts were initially slowed because the land was privately owned, either in large ranches or in the collective farms called ejidos. In 2000 a Mexican corporation, Cementos de Mexico began to purchase lands for conservation in the region. On CEMEX lands livestock and fences were removed and native vegetation encouraged. By 2006, CEMEX owned 195,000 acres in or near the Maderas del Carmen and managed another 62,500 acres. One of the important characteristics of the Sierra del Carmen is that it functions as a "corridor" enabling wildlife to migrate north and south. In the late 1980s the corridor between the Sierra and the mountains of west Texas enabled the black bear to disperse northward and reestablish itself in Big Bend National Park. The black bear had been extirpated from west Texas in the 1950s. In other initiatives, in 2000, CEMEX in cooperation with conservation organizations in Mexico and Texas began breeding and releasing to the wildbighorn sheep which had been absent from the Sierra del Carmen for more than 50 years. On October 24, 2011, Mexico and the United States signed an agreement for "Cooperative Action for Conservation in the Big Bend-Rio Bravo Natural Area of Binational Interest." In 2020, 19 plains bisons were transported from Janos Biosphere Reserve, and formed the second herd in Mexico to reestablish wild populations of bisons.