CABEZA PRIETA NATIONAL WILDLIFE REFUGE, Ariz. -- Mountains of trash, recurring fires, despoiled natural springs, vandalized historic sites and disappearing wildlife are part of the devastating toll that the government's running battle with smugglers and migrants is taking on national parks and wildlife refuges along the U.S. border with Mexico. In southern Arizona, the damage extends to American Indian and private land, jeopardizing a broad expanse of the Sonoran Desert, which boasts a greater diversity of plant and animal life than any other North American desert. At Cabeza Prieta National Wildlife Refuge, 2 1/2 million pounds of garbage is scattered...