The crossing of ‘El Jefe’: Famed jaguar circumvents US-Mexico border wall

The celebrated predator’s reappearance in Mexico is an encouraging sign for a species on the verge of extinction, but environmentalists warn that the newly-expanded barrier poses serious threats to wildlife

The jaguar known as 'El Jefe' (‘The Boss’) pictured in trail camera footage published by the University of Arizona.

For seven years, his fate was a mystery: no one knew what paths he had prowled, what prey had perished in the vice clamp of his jaws, or if he was even still alive. Some wondered if he had left any offspring in his wake. Many suspected he had died in some remote corner of the borderlands – a vast and tangled wilderness. But then, in early August, the jaguar known as El Jefe (The Boss) was photographed by a trail camera in northern Mexico – the first sighting of the famous feline since he was last spotted in the mountains south of Tucson, Arizona, in 2015.

El Jefe, one of longest-living jaguars documented in the modern US-Mexico border region, reappeared in the northwestern Mexican state of Sonora in early August, about 100 miles south of the border. “We don’t know when he crossed, or if he spent the whole year in Mexico or Arizona,” says Dr. Carmina Gutiérrez-González, Research Coordinator with the Northern Jaguar Project, one of eight organizations involved in Borderlands Linkages, a binational conservation initiative that works to protect jaguar habitat on both sides of the line. “We also have no idea where exactly he crossed,” the biologist added. Roberto A. Wolf, Gutiérrez-González’s colleague and the director of the project, says that El Jefe’s reappearance is great news: despite the hundreds of miles of walls, fences, and other barriers, “it means there’s still a chance for wildlife to move between one country and the other,” he says.

First spotted in the mountains southeast of Tucson in 2011 by a hunter, the last time El Jefe was caught on camera was in 2021, in Mexican territory. The picture was taken by PROFAUNA (Protección de la Fauna Mexicana A.C.), a conservation organization in Coahuila, Mexico, that also works with the Borderlands Linkages coalition. “For years, large jaguars have been recorded on both sides of the border,” explains the group’s director, Sergio Marines, who is celebrating the latest sighting of the famed jaguar. “This means that regional conservation work is bearing fruit.”

El Jefe was identified by his spot pattern – that beautiful coat of unique black spots that the Maya, who believed that wearing jaguar pelts bestowed them with the animal’s power, interpreted as constellations in the night sky. “The spots have a unique pattern, like our fingerprints, so it’s easy to identify them,” explains Gutiérrez-González, who has spent more than 20 years studying and tracking jaguars, the world’s third largest feline after the tiger and the lion, and the largest cat in the Americas, where its current range includes 18 different countries. “It’s also the most endangered carnivore in the region,” adds Daniela Medellín, a biologist with the Wildlife Ecology and Conservation Laboratory at Mexico City’s National Autonomous University of Mexico (UNAM).

“The jaguar’s range spans from northern Mexico to Argentina. There are some in the US Southwest, but that population is nearly extinct,” says Medellín, who helped conduct the most recent national jaguar census in Mexico.

There are an estimated 4,800 jaguars currently living in Mexico, concentrated primarily in the country’s Pacific coast and in the southwest. The Yucatán peninsula boasts the largest population, with protected areas such as the Calakmul Biosphere Reserve providing crucial forest habitat for the endangered animal. “With more than one million hectares of protected habitat, the number of jaguars has increased over the last 10 to 15 years, thanks to conservation strategies implemented in collaboration with governments, organizations and landowners,” Medellín says.

Despite this increase in population, jaguars continue to face numerous threats. The main danger is human presence, which every day encroaches into more and more of their territory. “These are animals that need a large area to move around in,” explains Medellín. “The average range of a male jaguar is anywhere from 90 to 200 square kilometers [35 to 77 square miles], but they can travel even greater distances,” Gutiérrez-González adds. “We have data showing ranges of more than 800 square kilometers [over 300 square miles].”

The border wall: A hazard for wildlife

In addition to the expansion of human settlements, road construction, and mining activities, “in our area,” the director of the Northern Jaguar Project says, “it’s obvious what the most serious problem is.” The project is headquartered in Tucson, Arizona, a city ringed by spectacular desert landscapes, where deep canyons descend from high mountain peaks. In 2003, the group purchased the massive Zetasora Ranch in the foothills of the Sierra Madre Mountains in northern Mexico, expanding the conservation habitat for the northern Jaguar by more than 54,000 acres. This Northern Jaguar Reserve provides a protected zone for populations in the Sonora-Arizona borderlands, where sections of fencing, walls and other barriers to humans and wildlife have fragmented the animal’s habitat.

Frontera entre Sonora y Arizona
A section of border wall cuts through the El Pinacate y Gran Desierto de Altar Biosphere Reserve, located on the border between the Mexican state of Sonora and the US state of Arizona, in 2020.Hector Guerrero

“And the habitat of many other species,” adds Miguel Gómez, the reserve’s administrator. The wall has not only caused serious harm to human life; it has also had “devastating effects on the fauna, impeding the passage and movements of carnivorous animals like bears, wolves, coyotes, and various felines, including mountain lions and jaguars,” Gómez says.

For centuries, borders and fences on the frontier impeded the movements of another of the continent’s largest mammals, and its largest herbivore, which also faces danger of extinction: the American bison. “Beginning in the 16th century, with the encroachment of cattle ranching and the advent of fences – when we see the first large cattle ranches – the migration of bison between the United States and Mexico has been increasingly interrupted,” explains Marines. “Historians have documented how settlement had a major impact on the continent’s populations of large mammals and their predators.” PROFAUNA, the organization Marines joined as a volunteer when he was 17, and which he now directs, is focused on buffalo conservation.

“The sheer scale of the border wall represents an unmitigated obstacle for jaguars, and for the prey they depend on, like deer and pronghorn,” Gómez adds. And it’s not just the visible part of the wall – those towering steel bollards that can be seen for miles – that impedes the passage of so many animals: “The underground foundation of the wall affects various rodent species, like prairie dogs,” Gómez says, adding that the wall “causes problems for birds as well.”

“The wall is a very serious problem, created as an unsuccessful solution to a very complex situation, which in turn has caused an environmental problem that requires an urgent solution,” Wolf says, when asked about President Joe Biden’s recent announcement that he would be completing unfinished sections of Trump’s wall in an effort to curb immigration between Arizona and Sonora – the main crossing area for jaguars. “I don’t have the solution to the complex social problem that migration represents, but building a wall like this isn’t a solution either, and its effects on biodiversity could be irreversible,” Wolf says.

Conflicts with ranchers are another cause of the jaguar’s near extinction in North America. Much like with wolves, “[ranchers] hunt them for alleged predation, claiming that they kill their cattle,” Gómez says. “But in most cases cows die for other reasons, and the jaguars just take advantage of a meal already served.” Wolf agrees: “All carnivores resort to carrion: it’s easier to eat an animal that’s already dead than to waste energy running after a live one.”

“Another major risk for jaguars is poison – a problem they often encounter in Chihuahua, for example,” Wolf says. “I remember one controversial case where ranchers poisoned a wolf that had eaten a cow. The worst part is that the poisons stay in the ecosystem and continue to have residual effects, which are passed down from one animal in the food chain to the next.”

“While trophy poaching of jaguars isn’t really a problem anymore, because no one would have the audacity to sell the pelts on the market, the animals continue to be eliminated in response to their supposed predation,” explains Marines, whose organization works with local residents to raise awareness of the problem. “If there’s a good balance of natural prey, jaguars will focus on that, and livestock will remain protected.” Gutiérrez-González says that in the Northern Jaguar Reserve, “jaguars feed on wildlife, especially deer and javelina, but they’re known to feed on over 150 different species.”

After more than two decades studying jaguars, Gutiérrez-González is one of the world’s foremost experts on the predators. “Long-term monitoring lets us learn a lot about their habits,” she says. “Until recently, most researchers thought that jaguars, who we knew could live many years in captivity, did not live more than 12 years in the wild. But we’re already seeing that they live longer than previously thought,” says the biologist, noting that El Jefe, who is 12 years old, offers a clear example.

Frontera entre Sonora y Arizona
Aerial view of the border wall in southern Arizona’s Coronado National Memorial, 2020.Hector Guerrero

El Jefe’s return to Mexico provides further proof of what conservation groups have been claiming for years: “The fact that jaguars travel across borders and that their territory spans both countries is no longer just a theory,” says Gutiérrez-González, who in the last 20 years has identified 176 individual jaguars in the Sierra Madre Occidental mountains, where the species’ total population remains unknown. “El Jefe’s return is further proof that these animals travel for miles and miles, from one side of the border to the other,” she says.

What biologists do know is that all of the jaguars in Arizona were almost certainly born in Mexico: “No female jaguars have been documented in Arizona,” Gutiérrez-González says, referring to the last several decades since the last female in the state was killed by a hunter, in 1963. “But the wall makes it really difficult to track and demonstrate the obvious fact that jaguars need to move unimpeded across the borderlands.”

In all its years of operation, Gutiérrez-González’s organization has only managed to document three cases of cross-border jaguars. Like El Jefe, these animals managed to outsmart a man-made wall that has proven lethal to their species, and to many others as well.

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