Continental Divide

A photographer documents the ecological impacts of the border wall between the United States and Mexico

Drought conditions in the Janos, Chihuahua, grasslands will force many species to move northward, like bison (below right).

Crouched in a photo blind near the border between the United States and Mexico, Krista Schlyer heard voices—beneath her. As if checking for a heartbeat, she pressed her ear to the ground to diagnose the source of the sounds. What she got was an earful of squeaks and chirps from a prairie dog family scurrying about in their burrow.

“I just lay there for an hour listening to them chatting back and forth,” Schlyer says. “It was an incredible moment.”

To untrained eyes, or ears, not much appears to live in the lands straddling the border between the United States and Mexico. And yet this region is one of the most biologically diverse in all of North America. The varied ecosystems include deserts, grasslands, “sky island” mountains and the Rio Grand Valley—the midpoint between the tropics to the south and the temperate zone to the north. More than half of North America’s bird species, 3,000 plant species and more than 100 different mammals inhabit the borderlands.

“If you were just looking at a place for its biodiversity, you have all the reasons you need to conserve this special part of the North American continent,” Schlyer says.

While most photographers rely on their eyes to help them understand a place, Schlyer interprets the U.S.-Mexico borderlands with all of her senses. It’s a good strategy in this arid desert region. Ground surface temperatures can soar to 160 degrees Fahrenheit, and according to Schlyer, “Most life is lived out of sight, under ground or by shadow of night.”

The last remnants of habitat in South Texas remain a haven for the plain chachalaca. Wall construction will put the preserve in a
no-man’s-land between the border wall and the Rio Grande.

How have so many species adapted to the harsh climate of the region? The desert tortoise can survive a year or more without access to water because its bladder stores large amounts of fluids. The Gila monster, a venomous lizard, consumes its annual energy needs in just a handful of large meals and spends 95 percent of its life underground. Trees such as mesquite, blue palo verde and ironwood have roots that penetrate deep into the soil to find moisture. Most cactus species have huge masses of shallow wide-spreading roots that can soak up water quickly. The mighty saguaro cactus has pleats that enable it to expand and contract as it takes up and uses water. Endemic and iconic to the Sonoran Desert, saguaros can live for more than 150 years and reach heights of 40 to 60 feet, providing much needed shade for other plants and animals.

While the survival of many species in the borderlands depends on conserving energy by staying put, others can only survive by constantly moving. Large mammals including coyotes, bobcats and foxes must travel to seek water, food and mates. Whether they venture into the United States or Mexico is irrelevant as long as they find what they need. But what if their survival depends on being able to move freely between the two countries? And what if they run smack into a giant concrete and steel wall? This is the issue that Schlyer addresses in her new book, Continental Divide: Wildlife, People, and the Border Wall (Texas A&M University Press).

Wildlife refuge staff Nancy Brown at a wall construction site.

The species that sparked Schlyer’s interest in documenting the impacts of an impenetrable border wall was the American bison. In 2007, the year construction of the wall began, she watched two bison jump over a broken-down barbed-wire fence as she flew above them in a small research plane. On the ground, she talked with landowners on either side of the fence, which at the time served as the international line separating the United States and Mexico. The U.S. rancher in Hidalgo County, New Mexico, and the Mexican rancher in the Janos region of Chihuahua told her that a bison herd hops the fence almost daily because the healthiest grassland is to the north and the main water source is to the south.

“It was an ‘aha’ moment for me,” she says. “Knowing where border policy was headed with plans to build a wall, and seeing the impact it would have on the bison, I knew how important this issue was to many species.”

For the next five years, Schlyer traveled extensively in the borderlands, photographing wildlife and talking to residents in both countries. She came to know and love the region, and described it as a place “where beauty and life spring out of a brown hard crust of ground; where rivers live in trees during the day and their beds at night; and where bighorn sheep carry maps of desert water in their brains.”

It’s also a place where the future of several endangered species depends upon the connectivity of the region, including the Mexican gray wolf, jaguar, ocelot, jaguarundi, Sonoran pronghorn and bighorn sheep. And, as the effects of global warming intensify droughts, animals like javelinas in Mexico that can’t adapt to changing conditions will need to migrate north. They’ll face a wall, and extinction. As individual species of the borderlands are impacted, entire ecosystems unravel.

After traveling the U.S.-Mexico border wall for 100 yards, looking for a place to cross, these javelina turned away. This stretch of wall in Arizona bisects the San Pedro River corridor, one of the last free-flowing rivers in the state and a haven for wildlife traveling north and south.

Just as the wildlife of the region share these lands, so have people for thousands of years. The earliest known inhabitants were the indigenous Hohokam and Tohono O’odham, followed by Apaches, Spaniards, Mexicans and Americans. It wasn’t until 1853, five years after the end of the Mexican-American War, that the Gadsden Purchase expanded U.S. holdings and set today’s boundary line between the United States and Mexico. The 2,000-mile border runs along parts of California, Arizona, New Mexico and Texas. On the Mexican side, the border touches the states of Baja California, Sonora, Chihuahua, Coahuila, Nuevo León and Tamaulipas.

Most border towns today are a testament to the region’s rich history of overlapping cultures, Schlyer says, and “abound in Spanish missionary-style architecture, roadside shrines, Mexican cuisine, native art and a Western mentality.”

While Schlyer has studied the immigration and national security policies that led to the construction of the border wall, she didn’t fully realize the impacts to people until her boots hit the ground. And while the media portrays the U.S.-Mexico border as a dangerous place of drug runners and illegal immigrants, Schlyer saw a different reality throughout her travels in both countries. Prior to 1994, Mexican migrants seeking work safely crossed the border at San Diego, California, and El Paso, Texas, cities with roads and infrastructure. In 1994, President Clinton launched “Operation Gatekeeper,” a U.S. immigration policy that tightened restrictions at these two crossings.

Desert tortoise with desert dandelion.

The policy was enacted with the explicit intention of forcing immigrants to cross the border in more remote areas, which would supposedly make it easier for border patrol agents to catch them. The results have been disastrous—more than 5,000 people have died of thirst and starvation in the harsh desert climate, and the lands and wildlife have been impacted by human trash, new roads and an influx of foot and vehicle traffic trampling sensitive habitat.

In 2007, construction of the wall began, and today one-third of the border consists of concrete barriers and steel fences, in some places extending 21 feet tall and dug six feet underground. The wall has exacerbated both the impacts to wildlife and dangers to people.

“One of the most difficult experiences I had was visiting the pauper’s graveyard in Holtville, Calif., where unidentified migrants found dead in the desert are buried,” Schlyer says. “I started my work to focus on the impacts of the border wall to the environment, but it’s impossible to separate the impacts to people because they’re so intertwined.”

From a photographic standpoint, Schlyer said her biggest challenge was accessing public lands near the border. Throughout her travels, she was routinely stopped and questioned by U.S. border patrol agents. Nearly 40 percent of the land along the U.S. side is public and includes places popular with photographers such as Cabeza Prieta National Wildlife Refuge, Organ Pipe Cactus National Memorial, Coronado National Monument and Big Bend National Park.

Kit foxes in the borderlands area.

“It’s a sad reality that our public lands on the border and our rights to enjoy them are now so restricted,” she says.

Since prehistoric times, people have always migrated from one place to another to find what they need to survive. In this respect, humans aren’t much different than wildlife. And, while a wall ultimately doesn’t stop people from crossing a border, it does stop wildlife from finding what they need to survive.

To help decision makers understand how special the borderlands are and shape the discussion around immigration reform, Schlyer is raising funds to give her book to every member of the U.S. Congress.

“The questions we should be asking are ‘how do we best share a border with a country whose economic realities are different from our own, and how do we protect the natural world that connects us and is precious to both nations?'” Schlyer says.

Part of the solution involves listening. Listening to the desert wind whistling among the sky island mountaintops, the howl of the Mexican wolf, to the rich music of the people and to the squeaky prairie dogs beneath the grasslands of the Chihuahuan Desert.

Krista Schlyer is a writer and photographer whose work has appeared in websites and publications for the national parks, Ranger Rick and Audubon. She’s an Associate Fellow with the International League of Conservation Photographers. You can view her work at