Up Against the Border Wall

On a quiet, late-spring morning in northern Sonora, Mexico, a beaver putters across a pond the size of a football field. A sinuous dam, 5 feet high, forms the pond’s southern edge. Frogs croak amid gnawed stumps, and the air is alive with birds and flying insects. “This is all new; this wasn’t here last week,” says Daniel Toyo, an agricultural technician with Naturalia, a Mexican environmental nonprofit. “It takes them three days to build something like this.” Naturalia manages the Rancho Los Fresnos, a 39-square-kilometer (9,577-acre) property that was once a working cattle ranch. Now, it’s a demonstration site for sustainable ranching techniques and conservation education. Los Fresnos encompasses the largest remaining group of ciénegas, or desert springs, in the watershed of the San Pedro River, which flows north into Arizona and joins the Gila River east of Phoenix. Most of the region’s desert wetlands have been degraded or destroyed by farms, ranches, and urban development. The beaver (Castor canadensis) stops to nibble on a floating branch. Then it heads for a den dug into the near bank, leaving a wake that spreads across the surface and disappears. The only sound is the breeze rustling the leaves of cottonwood trees, and the occasional bird song. Taking in this placid scene, it’s hard to believe that it could be so close to one of the most controversial international boundaries in the Americas. The Arizona border is just a 5-minute dirt-road drive north. Gerardo Carreón, Naturalia’s conservation director, walks a short distance upstream and points out rusty cans, socks, and pieces of burlap wedged among the rocks. “Border crossers often leave trash,” he says. “Drug smugglers wrap their feet in burlap sacks to hide their footprints. Sometimes word goes out: ‘Don’t be out on the property after dark.’” He points out flashes of light in the foothills of the Huachuca Mountains just across the border: the windshields of U.S. Customs and Border Patrol (CBP) trucks glinting in the sunlight. What appears as a tiny white oval hanging high above the vehicles is the CBP’s 200-foot-long helium-filled blimp with a radar system that can detect low-flying, drug-smuggling aircraft from 200 miles away. “I don’t think they’ve ever caught anything,” in part because smugglers have shifted their operations to the ground, Carreón says. Amid all this, the beavers most likely waddled or paddled south from Arizona, where their forebears were reintroduced in 1999; after all, much of the ranch’s northern boundary is nothing more than a barbed-wire fence. But that would change if President Trump follows through on his campaign promise to build a “big, beautiful wall” between the U.S. and Mexico...more