Note: along with the sidebar at left, a separate editor's note accompanies this story.

At 6:30 on a warm spring morning, a brightly colored summer tanager flits above green cottonwood, willow and sycamore trees. Lower down in the forest, a vermillion flycatcher darts from one mesquite branch to another. A piercing cry -- "ke-er" -- draws attention to a gray hawk perched on a bare branch, and a Bell's vireo inquires, "Cheedle-cheedle-cheedle-chee?" as it flies through the tree canopy. It's a noisy avian symphony, underscored by rustling winds and the burble of a creek.

This could be a scene on the banks of Arizona's San Pedro River, where a federally protected United States conservation area has attracted hundreds of bird species, along with international recognition as one of the Southwest's best remaining riparian riverfronts. But this birder's paradise lies along Río Cocóspera, 30 miles south of the U.S.-Mexico border, in a private preserve in the Mexican state of Sonora.

Landowner Carlos Robles Elías, a trim, 5-foot-6-inch 57-year-old, his black hair streaked with gray, expresses pride in the biodiversity found on his 10,000-acre portion of Rancho El Aribabi, which has been in his family for three generations. Much of it has been created by his own renegade ranching practices. For a decade, he's whittled down the number of cattle he runs, to reduce grazing impacts, while building a new ecotourism business and selling trophy deer hunts. In a camouflage baseball cap and hiking boots instead of the usual cowboy outfit, he radiates seemingly endless energy as he drives a reporter around his spread during a two-day visit. Underneath a tree high in the Sierra Azul mountains, he reflects on the changes he's made: "Before, it was just for making a living. ... Now, I feel so good. I'm making a difference. Siento que soy alguien. I feel like I'm somebody."

He stops to repair a damaged water tank, replacing a bent plastic pipe with a metal pipe. It's part of a network of 32 small tanks and 20 miles of underground pipe he has installed to benefit cattle and wildlife on the ranch. But later, as he walks along a path beside the river, he turns and speaks candidly: "Please print that we need help."

He needs help because he's trying to be an agent of change and also make a living. Traditional cattle ranching has dominated Northwest Mexico since the 1600s. More than 80 percent of Sonora is grazed by livestock, and the ranching culture and economy are as entrenched here as they are in the rural Western U.S. Yet Robles is not entirely alone on his path toward reforming ranching: A few U.S. conservation groups have reached across the border to support restoration efforts on his and other Mexican ranches. Mexico's government and some Mexican groups are also involved, in a trend that's similar to but smaller than what's happening on U.S. ranches. Mexico's ranches are important to conservationists in both countries for many reasons, including the tremendous biodiversity of this part of Mexico and the crucial wildlife corridors that straddle the border.

Robles' efforts have earned the admiration of many scientists and conservationists on both sides of the border. His ranch has become a symbol of hope in the midst of the region's notorious troubles -- the illegal traffic in undocumented immigrants and the terrible Mexican drug cartel violence that has killed nearly 50,000 people in the last five years. His stretch of Río Cocóspera holds one of the area's few remaining intact marshy cienegas. Farther uphill, in the Sonoran and Chihuahuan desert uplands, waist-high grasses ripple, and there's a jungle of blue oaks that tops out at 6,000 feet elevation. He's providing habitat not only for the Coues white-tailed deer -- much coveted by hunters -- but also for jaguars, ocelots, coatimundi and dozens of other species that the Mexican government considers imperiled.

Last spring, when HCN visited the ranch, it looked wonderful. Robles had finally reduced his cattle from 1,100 head all the way down to zero -- a key move, he believes, in restoring the land from previous abuses and keeping the ecosystem healthy. "I don't like the way ranchers think," he said -- traditional ranchers, that is.

But Robles' income from birdwatchers and hunters has declined drastically over the last few years, mainly because the much-publicized drug-cartel violence has discouraged potential customers. And he hasn't been able to get as much help as he'd hoped for from conservation groups and agencies. So since last spring, he's had to put about 1,000 cattle back on the land, to scratch out a modest income from beef production. Last October, he emailed that his long-term goal was still zero cattle, adding, "I feel bad, for sure, because I'm walking back."

In broken English, Robles elaborated on the effects of reintroducing cattle, in another email a few weeks ago: "We are seeing so shorter grass ... in the deeper or microscopic life (it) means a lot. ... the health of the ecosystem will be decreasing slowly like a chronic sickness, and of course, erosion ... the impact is (also) emotionally because I have a different vision ..." His continuing struggle highlights both the good news about conservation in Mexico, and the unique and at times almost overwhelming difficulties.

Robles' great-grandfather bought what is now Rancho El Aribabi in 1888, and generations of the family have remained connected to the land. Robles grew up in Nogales, a border town where his father ran restaurants, but he often visited the ranch. At a young age, he fell in love with cattle roundups and horseback riding. He was also fascinated by nature, collecting butterflies and bugs and devouring nature encyclopedias instead of the comic books his friends preferred. Even back then, he says, his family and other ranchers worried whether cattle were sustainable. The acreage grazed by livestock in Mexico soared 260 percent from 1950 to 1990, and, Robles recalls, "I would hear too many times from neighbors that they would bring in more cattle because the rain was big enough ... but suddenly the rains stop. No rain, no grass. Then they would say, 'What are we going to do?' "

One of his brothers, Eduardo Robles, says that early on, "a seed was planted in Carlos' heart, this belief that something was not working well for nature. ... He would talk about trees, grass, the environment. He liked being a cowboy, (but then) changed his mind and said, 'We can put the ranch to other uses.' "