BROWNSVILLE, Texas - When it comes to smuggling animals across the U.S.-Mexico border, U.S. Wildlife Inspector Ed Marshall has seen it all. Exotic birds given Valium or tequila so they stay quiet through Customs inspections. Sleeves moving with hidden reptiles. Wildcats stashed in trunks. Last week, the Border Patrol seized two white tigers on their way to Mexico. And in 2001, an African elephant was smuggled across the Gateway International Bridge on a truck. "They call it the 'Dumbo Case,'" Marshall said, shaking his head. The contraband is part of a global trade in endangered wildlife estimated by the U.S....