 The reserve includes both dry Chihuahuan Desert shrublands and forested sky island, high-elevation enclaves of Sierra Madre Oriental pine-oak forest.The reserve is home to 400 bird species and 70 mammal species, including the American black bear ("Ursus americanus"), collared peccary ("Pecari tajacu"), and cougar ("Puma concolor").The region was designated a biosphere reserve in 2006.