The border wall threatens decades of binational wildlife conservation

Binational groups are preserving migratory corridors and restoring degraded areas in the Borderlands. Will the landscape be severed?

One sunny morning in March, I followed Valer Clark on a walk into the wooded hills that surround her property, an old ranch deep in southern Arizona’s Chiricahua Mountains. For such an arid region, it’s surprisingly lush: Streams gurgle, the soil is dark and loamy, and the hillsides are blanketed in green.

Clark, who is 79, has bright blue eyes that widen when she describes anything that astonishes her, which happens often. But she’s especially amazed by the transformation that has occurred on her land, where timber was logged for the sawmills that powered Arizona’s copper boom. “This wasn’t the way it was,” she told me, gesturing at the almost oasis-like surroundings.


Clark wanted me to see what it used to look like, 40 years ago, when she and her now ex-husband, Josiah Austin, first bought the El Coronado Ranch on a whim. We walked toward the base of a slope, now bare from a recent wildfire. “A lot of the ranch looked like this,” she said, reciting the litany of abuses El Coronado has suffered, starting in the second half of the 19th century: deforestation, overgrazing and then erosion. By the time Clark and Austin arrived in the early 1980s, the soil was thin and hardly any grasses grew on the surrounding hillsides. At first, she wondered what happened, why nature was destroying itself, but when she looked into the history, she realized that the damage had been caused by humans.

To restore the land, the couple built more than 20,000 small loose-rock dams, called trincheras, on El Coronado’s 1,800 acres (the property includes 16,000 acres leased from the U.S. Forest Service) over the next 20 years. When rain fell, the dirt would accumulate behind the structures, trapping water like a sponge and allowing vegetation to take root. Before, she said, the water roared through and disappeared. “Now the trincheras slow down the flood and the water trickles back into the mountain.” Thanks to these structures, which range from a few feet to 20 feet wide, vegetation and insects have returned, attracting animals like deer and mountain lions in far greater numbers than had been seen in many decades.

THAT TIME SPENT BUILDING trincheras around El Coronado laid the foundation of Cuenca Los Ojos, a nonprofit organization that the couple started in 1990 to spearhead landscape-scale restoration projects in the greater Madrean Sky Islands, an ecoregion that stretches from western New Mexico and eastern Arizona south into the northern Mexican states of Chihuahua and Sonora. Named for a series of mountain ranges that rise like islands from the desert floor to as high as 10,000 feet, these isolated ranges connect the two spines of the Americas: the Rocky Mountains and the Sierra Madre Occidental. With that convergence comes an unusual amount of biodiversity; neotropical plants and animals like agave and jaguar mingle with pine trees and black bears. A day’s walk can take you from the ecological equivalent of central Mexico to the Canadian border.

Valer Clark jokes with Cuenca los Ojos Director of Operations, Jose Manuel Perez (left) and other local ranchers at Rancho San Bernardino in 2013.

Eleven different properties make up the ecological restoration portfolio, the majority of them in Sonora. They link up with protected areas on the U.S. side of the border, such as the San Bernardino Wildlife Refuge east of Douglas, Arizona, and private ranches in the nearby Malpai Borderlands, creating large connected landscapes through which wildlife can easily migrate. Students, scientists, land managers and ranchers on both sides of the border have come to appreciate their importance and advocate for their conservation.

But as the Trump administration increases its efforts to wall off the entire southern border, their conservation efforts — and the ecosystems they protect — are under growing threat. Thirty-foot steel walls are cutting across federally protected areas and through some of the most rugged, remote and ecologically sensitive environments. And with the physical barrier comes another kind of blockade, one that threatens the cross-border skill-sharing and collaboration that are essential to protecting the landscape shared by the two countries. 

As we walked along a marshy path filled with animal tracks, Clark lamented how, with the new sections of border wall going up, those corridors she has helped protect will become a dead end — for both wildlife and people. “We’ll have nothing to show them,” she told me, referring to the education initiatives that Cuenca Los Ojos organizes to promote cross-border conservation work. “(The border wall) is cutting off one of the most important resources this country has.”

“(The border wall) is cutting off one of the most important resources this country has.”

EL CORONADO LIES TWO HOURS east of Tucson, at the end of an 8-mile dirt road that leads up into the Chiricahua Mountains, home to the Chiricahua Apache, who were forcibly removed in the late 19th century. As you approach the ranch, dry grasslands give way to pine and oak trees that enclose the road in a green canopy. Birds chirp from above and water bubbles along in a roadside stream.

“A lot of people think that the border is a wasteland,” Clark told me, sun streaming into her living room. She ended up here by accident; she grew up in New York City, where she spent much of her childhood playing in Central Park and drawing animals at the zoo. It was her introduction to wildlife, she said. “Perhaps that’s where it all started.”

In the early ’80s, Clark and Austin visited Austin’s brother in Tucson and decided to check out El Coronado, which was for sale. Clark bought the ranch and became so fascinated with the earth under her feet that she had no desire to return to her old life in New York. “If you’re really a landowner, you can’t leave the land,” she thought, and made plans to move permanently to Arizona.

After learning that Cajón Bonito, a stream in Northern Sonora, was one of the few places where the endangered Yaqui Chub was still found, Clark purchased two ranches abutting the stream in an effort to help save the fish.

SOON AFTER SHE MOVED to El Coronado, Clark noticed how water accumulated in certain areas —behind naturally occurring rock barriers, where little patches of soil and vegetation could be found. It was her “light-bulb moment,” she said. For thousands of years, Indigenous communities in the southwestern U.S. and Mexico had used rock dams to grow their crops and control erosion and flooding. The couple hired workers from the mountains of central Mexico, where they used similar structures to plant corn, and began building trincheras all over El Coronado.

Clark imagined it would be just a local effort, but a decade after they began, scientists took notice of how well the native landscape was recovering. Wendell Minckley, for example, a fish biologist with the Arizona State University, was studying the Yaqui chub, a native species on the brink of extinction in the Río Yaqui watershed, the largest river system west of the Continental Divide. Minckley convinced Clark that she could help save the chub, which still survived in the Cajón Bonito, a small stream in the mountains of northern Sonora. It might be one of the most important streams in North America, he told her. “Go down and take a look.” Clark did, and later bought two ranches abutting the stream, hoping to protect the fish’s remaining habitat and boost its chances of survival.

A few years later, Clark established Cuenca Los Ojos as a private foundation and began focusing her efforts south of the border, purchasing three more ranches in northern Sonora. Rancho San Bernardino, which she bought in 1999, formed an important binational wildlife corridor with the San Bernardino Wildlife Refuge across the border in Arizona.

The old ranch provided a refuge for migrating wildlife, but a century of overgrazing, alfalfa farming and gravel mining had dried up the wetland, and much of the wildlife disappeared. Clark saw an opportunity: “If I could take a piece of land that was that degraded and turn it around, it would show that you could do it anywhere,” she said.

To restore the property, CLO built gabions — larger rock dams held together by wire cages — across its streams and washes. Within a decade, the wetland came back. Wildlife cameras later showed that animals were returning as well and migrating through the area — black bear, mule deer, white-tailed deer, puma, ocelot, bobcat.

A gabion under construction at Rancho San Bernardino in 2013.

From the beginning, much of this work has relied on building relationships across the border with ranchers, scientists and other conservation groups. In the early years, before there was a wall or even a barrier across much of the southern border, forging those relationships was easier, Clark told me. Ranchers in Mexico would visit and have coffee with their neighbors in the U.S., and whenever somebody’s cow wandered across the line, they would help each other retrieve it. Then came the attacks of Sept. 11, 2001. Suddenly, those relationships were more difficult to sustain: Barriers went up, border enforcement increased, and people became more fearful. “It just shut down communication,” Clark said.

A few years later, in 2005, the National Environmental Policy Act and Endangered Species Act were suspended as the U.S. government converted miles of existing wooden vehicle-barrier fencing in Arizona and New Mexico into 30-foot-tall steel bollard border walls.

Still, Cuenca Los Ojos continued its restoration work, while conservation groups like the Sky Island Alliance and the Wildlands Network focused on developing relationships with their counterparts in Mexico, working on binational concerns like restoring watersheds and managing the critically endangered jaguar, which breeds in Sonora and then migrates north into southern Arizona. A new “large landscape” conservation philosophy of conservation took hold as ecosystems grew increasingly fragmented from human development. Rather than focusing on a single parcel of land, this approach focused on actions taken across large areas, often involving many private landowners, government agencies and conservation organizations.

The sun breaks through clouds in the hills looking towards Valer Clark's property.

THE DAY AFTER I VISITED Clark at El Coronado, I drove 60 miles south to Agua Prieta, in the Mexican state of Sonora, to meet Jose Manuel Perez, CLO’s director of operations in Mexico. It was pouring rain as I passed through the port of entry and headed out of town and east along northern Mexico’s main artery, Highway 2, through rolling agave-studded desert and mountains shrouded by mist. Most of the sky islands lie south of the border, but Mexico, unlike the U.S., lacks large tracts of federally protected land. And so protecting them requires a different approach: convincing individual ranchers and ejidos — communally owned agricultural land established after the 1910 Mexican Revolution — to voluntarily adopt conservation practices.

Perez told me to meet him by an unmarked white gate on Highway 2 at the entrance to Cuenca los Ojos’ Rancho San Bernardino. Perez, who has dark brown eyes, wore a cowboy hat and boots. He speaks softly, in lightly accented English, which he learned as an exchange student in North Dakota back in the 1980s. “It was a cold winter,” he told me, reminiscing.

Born into a ranching family in Coahuila, the Mexican state east of Chihuahua, Perez worked for Pronatura Noroeste, a Mexican nonprofit. Seven years ago, he joined CLO to run its new sister organization, Cuenca de los Ojos AC. (AC stands for asociación civil, a type of nonprofit in Mexico.)

At first, when Clark approached Sonoran ranchers about conservation, Perez said, they were skeptical and sometimes downright hostile. CLO had removed cattle from the old San Bernardino Ranch and was building gabions all over the property to restore the wetland. Nearby ranchers were worried that it was taking their water, Perez told me. “La señora, she’s crazy,” he said, quoting the ranchers.

The overgrowth of native grasses around this gabion on one of Valer Clark's properties is evidence of the efficacy of the method for helping to restore the habitat.

But when they saw water levels rise on their own properties, they became more receptive. With San Bernardino’s land greatly restored, Perez decided to begin rotating cattle on parts of CLO’s properties to develop sustainable grazing strategies and help further CLO’s outreach to the Sonoran ranching community. “Once we put the cattle on, it changed the way they saw us.” It was easier to approach them about other issues, Perez told me.

We drove north toward the border, less than a mile away from Perez’s office. Back in the early 2000s, this was a higher-traffic area for migrants looking to cross into the U.S., Perez told me. But after the U.S. government installed high-powered 80- to 160-foot surveillance towers in 2016 around the San Bernardino Wildlife Refuge, the number of border crossers plummeted. Now, the Trump administration is building a wall here anyway — to the tune of $14 million per mile for the 20-mile stretch planned through the refuge. 

Perez stopped the truck at the top of a small rise leading down to the line of willows and cottonwoods that mark the Río San Bernardino and the borderline just beyond. “We try to keep it as disturbance-free as possible for the wildlife,” he said.

From our vantage point, the border was still a wooden fence lined with barbed wire, the kind that allows most animals to pass through. Last year, a wildlife camera installed on another CLO property, Rancho El Diablo, six miles east of San Bernardino, showed a jaguar passing through. After many years of absence, the elusive cat had returned. “It was really exciting,” Perez told me.

A mountain lion is captured by a trail camera in February, in the border region near San Bernardino
Myles Traphagen/Wildlands Network

NO ONE KNOWS exactly how new border wall construction projects will impact wildlife populations and environmental health in the borderlands. Juanita Sundberg, an associate professor of geography at the University of British Columbia, told me it has been over 15 years since the U.S. government conducted an environmental impact study on the immediate, cumulative and long-term effects of border enforcement policies.

One day this spring, I joined Emily Burns and Megan Bethel from the Sky Island Alliance as they installed wildlife cameras along a stretch of the border in the foothills of the Huachuca Mountains, about 50 miles west of San Bernardino. The day’s mission was part of a broader effort to install 60 wildlife cameras along some of the most remote and rugged stretches of the border in the U.S. and Mexico to get crucial baseline data about the wildlife communities before their habitat and movement change. The places in question don’t yet have a wall, though some stretches have a vehicle barrier.

“The wall is potentially coming everywhere, so we’re planning for that,” Burns, who is leading the study, told me matter-of-factly. “If the wall is built, where are the first places it needs to come down to restore wildlife connectivity?” Even as the wall is being built, Burns and other advocates are planning for its removal.

If the wall is built, where are the first places it needs to come down to restore wildlife connectivity?”

The previous winter, Burns and several colleagues interviewed a group of Sonoran ranchers near the Río Bavispe, part of the larger Río Yaqui cross-border watershed. The goal of the interviews was to develop a collaborative conservation model — bringing the ranchers’ properties into Sky Islands’ wildlife-monitoring network so researchers could document the species on their lands and in turn, learn about the ranchers’ economic needs. Still, Burns worried about how cross-border initiatives will continue if a wall ends up cutting off the corridor they’re trying to protect. “Fundamental components of what we’re trying to conserve will be impacted,” she told me. “That’s why we need to be collecting data now and continuing to monitor them now so we can come up with the next best conservation strategy. … It’s like trying to balance a table with 1,800 legs.” 

The eleven large properties on both sides of the US-Mexico border that form Cuenca Los Ojos have helped to restore habitat and preserve migratory routes for the many diverse species of the Northern Sonora region.

BURNS STOPPED THE TRUCK at the side of a dirt road and began walking to the spot the Sky Islands volunteers had pinpointed for one of the camera placements, at the base of a gully with a game trail running along the bottom. The camera has a sensor that detects heat and motion, which triggers filming of any animals.

We were in the middle of rolling grasslands, the wind rippling them like waves in a sea. Periodically, I looked towards the border, trying to see where the U.S. ended and Mexico began, but everything just looked the same. A giant white surveillance blimp hovered in the sky above us, watching, reminding us of the challenges of this type of conservation in an increasingly militarized landscape.

But trees covered the once-denuded hillsides of El Coronado, and at San Bernardino, a formerly dried-up river was running again. Places can heal if we give them a chance,” Clark had told me a few days before.

Burns and Bethel headed off to place another camera while I hung back. From the inside of the truck, I saw a coyote through the grasses, perhaps 100 yards in front of me. He stopped to look at me briefly and then continued on, bounding across a gully and then up the hillside, before disappearing over the top towards the still partially open border.

Sarah Tory is a correspondent for High Country News. She writes from Carbondale, Colorado. 

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Note: This story was updated to correct the university Wendell Minckley works for. He is a fish biologist with Arizona State University not the University of Northern Arizona.