Illegal immigrants? How the border wall would block jaguar from critical habitat.

The Sky Islands region of southern Arizona provide critical habitat for jaguar as well as other endangered and threatened species. Photo by Stephen Eginoire


In a grainy black and white video, a furtive figure casts his gaze from side to side. It’s nighttime. Moths flitter in front of the camera and Sombra’s eyes glow like two full moons. The video is high contrast and pixelated, like footage of a fugitive caught on a security camera. Unaware he’s being filmed, Sombra holds his head up, alert to opportunity and danger. Both may find him in the Chiricahua Mountains of southern Arizona.

            Sombra (Spanish for “shadow”) is a male jaguar, the largest cat in North America and third in size only to lions and tigers. He weighs between 120 and 210 pounds, measuring nearly three feet tall at the shoulder. His tawny, golden fur is flecked with a camouflage of black rosettes. His shoulders and limbs are thick and muscular, making him a powerful climber and swimmer. And his head is round with a strong jaw and long canine teeth, allowing him to pierce the skull of his prey. Sombra is one of seven male jaguars known to have crossed the US-Mexico border since 1996; an unwitting immigrant caught in an emotionally charged debate over a border wall.

            Though commonly pictured in a Central American jungle, the jaguar once prowled throughout the southern United States, from California to Louisiana.

            “According to geological records, jaguars evolved in today’s United States thousands of years before they expanded their range into South America,” says Michael Robinson, a Conservation Advocate at the Center for Biological Diversity. “They were all over North America.”        

            However, as human populations grew jaguars came to be regarded as a threat to livestock. The 20th Century saw the extirpation of the American jaguar. With a government-backed bounty on its head, the jaguar was trapped, poisoned and shot by ranchers and hunters. The last American jaguar was killed near Tucson in 1965. Although it became illegal to kill them in Arizona four years later, they were left off the endangered species list when it was created in the 1970s.

            Decades passed. Jaguar populations throughout Mexico and Central America shrunk to less than 50% of their historic range due to habitat loss and hunting. They became extinct in both El Salvador and Uruguay, and for the most part, all hope was lost that they would ever return to America. Then in the late 1990s, two serendipitous events occurred: the jaguar was added to the endangered species list, and two male jaguars were spotted in southern Arizona. There was a surge of public interest around the big cat and conservationists saw an opportunity for a comeback.

 A large male jaguar known as El Jefe, camera trapped in the Santa Rita Mountains south of Tucson.  Photo courtesy of the  Center for Biological Diversity .

A large male jaguar known as El Jefe, camera trapped in the Santa Rita Mountains south of Tucson. Photo courtesy of the Center for Biological Diversity.

            The Santa Rita Mountains, some forty miles north of the border, are marked by sharp, rocky peaks and barbed ridges. From the sunstruck valleys of the Sonoran Desert, the mountains rise 6,000 feet into the sky. Like Jack’s beanstalk, the ecosystems woven into the peaks and canyons are a world apart. The Santa Rita Mountains are one of the most biologically diverse regions in the United States with species like the golden eagle, black bear, and coatimundi, a rare raccoon-like animal. It was near here that El Jefe, a young male jaguar, was treed by a hunter’s dogs in 2011. The hunter snapped a few photos of the snarling cat before gathering his hounds and retreating. But that wasn’t the last of El Jefe. Trail cameras throughout the area captured him on film over 100 times.

            El Jefe became a celebrity. For a time he was the only known jaguar to reside in the United States and his fame helped boost opposition to an open-pit copper mine. When El Jefe disappeared in 2016, it led many to believe he crossed back into Mexico, perhaps in search of a mate; illustrating one of the biggest challenges to recovering an American jaguar population: there hasn’t been a documented female in the United States since 1963.

Map courtesy of Anna Riling

            The closest breeding population of jaguars is believed to be in Sonora, loosely dispersed throughout the Sierra Madre. If jaguars were to reclaim their former territory north of the border, a significant number of females would need to make the crossing as well. And what then? Is there still room for the biggest cat in North America? According to conservationists, the answer is yes—in New Mexico’s Gila National Forest, in the mountainous Sky Islands of Arizona, and on the Mogollon Rim, the southern escarpment of the Colorado Plateau. All jaguars have to do is get there.

An environmental carte blanche

The US-Mexico border stretches 2,000 miles from the Pacific Ocean to the Gulf of Mexico. It crosses three mountain chains, two deserts, and 25 million acres of protected U.S. public land. There are wilderness and conservation areas, tribal lands, and six national parks along the border. And, despite President Trump’s rhetoric, a third of it is currently fenced in some fashion; be that by 12-to-18-foot wire pedestrian walls, vehicle fences, or Bollard-style steel slats. There have been multiple attempts to secure the border since the 1990s, with much of the construction occurring during the Obama Administration as a result of an act signed by President George W. Bush. 

            While politicians have debated the effectiveness of a barrier to prevent illegal immigration and drug smuggling for decades, the call for a “big, beautiful wall” became one of President Trump’s most notable campaign promises. That and his claim he would make Mexico pay for it. Just five days into his presidency, President Trump signed an executive order to extend the barrier. Since then, there have been various legal challenges, budget showdowns (and shutdowns), and vacillating messages from the White House. While neither Congress nor Mexico have approved funding for a full-length barrier, the federal government has begun quietly replacing existing fences. The Trump Administration’s first wall contract will rebuild a two-mile section of fencing in California. Another twenty-miles is scheduled to be replaced in New Mexico this year.

            The devastating impact a 2,000-mile barrier wall would have upon the many endangered species living in the region isn’t hypothetical. Conservation biologists have already documented the effects of existing fences. In one study, scientists documented a decrease in mountain lion and coati sightings in areas near a barrier wall in comparison to those without. Conversely, the number of humans caught by the camera traps did not decrease in the presence of a barrier.

            “The thing about border walls is that they don’t stop people. They stop wildlife,” says Dan Millis, a Borderlands Program Manager for the Sierra Club Grand Canyon Chapter.

            According to the Center for Biological Diversity, the proposed border barrier and its surrounding infrastructure would impact 93 endangered, threatened, and candidate species; destroying critical habitat for 25 of those. Normally federal protections offered under the Endangered Species Act would require extensive environmental impact studies and approval by the U.S. Fish and Wildlife Service before any major development—like a border wall—could proceed. But all that changed after the terrorist attacks of September 11th. In 2005 President Bush signed the REAL ID Act, a measure designed to enhance Driver’s License and ID card security, but also included additional provisions for the Department of Homeland Security (DHS). The REAL ID Act allows the DHS to waive 37 federal laws, including the Endangered Species, Clean Water, and National Environmental Policy Acts. Waivers have been used five times to construct much of the existing border wall. The act essentially gives the government a carte blanche to override any environmental protections along the border.

 View of the pedestrian border wall along the southern slopes of Arizona's Huachuca Mountains, a barrier that severs habitat critical to endangered and threatened wildlife.  Photo by  Stephen Eginoire

View of the pedestrian border wall along the southern slopes of Arizona's Huachuca Mountains, a barrier that severs habitat critical to endangered and threatened wildlife. Photo by Stephen Eginoire

Pushed to the brink

When a jaguar roars, his powerful jaw gapes open, revealing two sets of ivory white teeth. His muscular rib cage expands and contracts with each guttural grunt. Jaguars prefer living and hunting in solitude, but will communicate with one another by roaring. The only cat in North America to do so.

            Jaguars can occupy territories as large as 30 square miles, depending on the density of available prey. An opportunistic hunter, the American jaguar will eat everything from birds and mice to deer and elk, but rarely people. In the dry borderlands of the American Southwest, they would more than likely maintain larger territories than in the abundant jungles of Central America, potentially meaning fewer numbers overall. But even a small American population could improve the health of the jaguar species as a whole.

            Despite conservation efforts in Sonora, jaguars are increasingly under threat from habitat loss, segmentation, and hunting by local ranchers. If they could successfully expand their territory north of the border, it would reduce the risk of inbreeding and create a larger gene pool in the region.

            “Marginal populations can be important to species’ genetic diversity and may be important to future species’ evolution, especially against a background of environmental change,” wrote Jesse Lasky, an Assistant Professor of Biology at Penn State University, in a study on wildlife and barrier walls.

            Imagine a 30-foot wall sunk several feet into the ground, or better yet, search for images of the eight border wall prototypes recently completed in California. Such a structure would prevent jaguars and other endangered species from crossing the border, blocking connectivity between wildlife populations and decreasing genetic diversity.

            “If you decrease genetic diversity you can end up with problems like inbreeding,” Lasky says. “Loss of genetic diversity will only emerge over a number of years, but it can threaten the ability of a species to adapt to new parasites or changes in their environment like climate change.”

 Mexican gray wolf, another species whose survival depends on borderlands habitat.  Photo by Robin Silver.

Mexican gray wolf, another species whose survival depends on borderlands habitat. Photo by Robin Silver.

            The jaguar couldn’t be a better mascot for the case against a border wall, but the truth is that nearly 100 other plant and animal species could be pushed to the brink of extinction by it too. The Mexican gray wolf, which was hunted out of the United States in the 1930s, now has a small population of 113 in Arizona and New Mexico. Their survival relies upon their ability to mate with their Mexican counterparts. The Sonoran pronghorn is in a similar situation. With less than 1,000 of them in both Mexico and the United States, the pronghorn’s future depends on it maintaining a diverse gene pool on both sides of the border. It also demonstrates another major problem for wildlife should the border wall be completed. The pronghorn travels far and wide across the desert and a wall could prevent them, as well as other wildlife, from accessing food and water.

            With warming global temperatures already altering and destroying wildlife habitats, many more animals will be on the move in the future.

            “The preferred climate for any given organism is probably going to be somewhere else in the future,” Lasky says. “For those distribution shifts to happen, they have to be able to move.”

            Many of the species endemic to the borderlands are adapted to very specific climates and precipitation patterns. Climate change will cause numerous wildlife species to migrate into the United States in search of suitable habitats.

            “If you’re talking about a species that’s already pushed to the brink and you take their ability to adapt to climate change away…” Millis trails off, but the implication is clear. A border wall would prevent wildlife from finding the habitat they need to survive.

A surge in biological diversity

The video of Sombra peering into the night is just twenty seconds long. At the end, he pads off screen with a quiet rustle of dry grass. The video, shot in the summer of 2017, was the last sighting of Sombra. Has he wandered back to Mexico? Or is he secretly searching the remote Arizona mountains for a mate?

            A population of American jaguars could have a profound effect on the borderlands ecosystem. The jaguar is an apex predator and sits at the top of the food chain, managing the overall health of the ecosystem by regulating prey populations and increasing biodiversity.

            When wolves were reintroduced into Yellowstone during the 1990s, the large elk population was hunted to a more sustainable level. Scientists observed a dramatic regeneration of trees like the aspen and cottonwood, and with them the return of songbirds to the park. Beavers arrived and began building dams, creating habitats for otters, fish and waterfowl. The biodiversity within Yellowstone increased dramatically over the following twenty years. From the genetic to the global level, biodiversity describes the variety of living organisms that contribute to the health of an ecosystem. Even if you look at it from an anthropocentric point of view, biodiversity provides more than a pleasing landscape to look upon. It supplies us with food, water, and clean air.

            What would the borderlands ecosystem look like with the return of the jaguar? Would we see a surge in biodiversity like Yellowstone? Would the jaguar’s presence enable other species to return? One thing is certain: we’ll never find out if the border wall is completed. TG