According to a US Fish and Wildlife Service provisional report released last year, a wall covering the entire 2,000-mile border, with approximately 1,000 feet of developed space on either side,would potentially impact 111 endangered species, 108 species of migratory birds, four wildlife refuges and fish hatcheries, and an unknown number of protected wetlands. The Rio Grande Valley is one of the most biodiverse places in North America, with some 700 species of vertebrates alone, and rakes in $463 million a year from wildlife watchers, like birders, who come to witness thousands of birds flying through on great migrations. Bobcats, javelinas, ocelots, deer, some 500 species of migratory birds, and scores of amphibians and reptiles all depend upon free movement through this region.