When biologist Ganesh Marin first observed a jaguar on a preserve in northern Sonora, Mexico, in 2020, he was elated. The feline continued showing up on Marin’s grid of camera traps along the Arizona border, which indicated he was making the region his home. Marin nicknamed the jaguar El Bonito, Spanish for “the beautiful.”
But in 2021, Marin, a National Geographic Explorer, noticed something odd about the photos. The spot patterns appeared to vary ever so slightly from one picture to the next. Further examination confirmed that he was indeed seeing not one, but two young male jaguars.
It had been thrilling enough to watch Bonito develop on camera, “growing up, getting bigger, growing a thicker neck and bigger head,” Marin says. But realizing it was more than one: “That was pretty exciting.”
The presence of a second jaguar a couple miles south of the Arizona border provides yet more evidence that the big cats are moving north to reclaim old territory, says John Koprowski, a biologist and dean at the University of Wyoming and Marin’s Ph.D. advisor. (Related: Why a new jaguar sighting near the Arizona-Mexico border gives experts hope.)
As recently as the early 1900s, jaguars were found as far north as the Grand Canyon and south all the way to Argentina. But hunting, often government-sponsored, wiped them out of Arizona and New Mexico, the northern expanse of the jaguar's range, by the mid-20th century.
Marin named the second jaguar Valerio, after Valer Clark, a conservationist who founded the organization Cuenca Los Ojos. This bi-national environmental organization now manages a 121,000 acre wildlife preserve along the border in Sonora, where Marin does his research as a doctoral student at the University of Arizona.
The cats could expand their territory to the north if humans let them, but they face obstacles such as roads and the U.S.-Mexico border. More than 450 miles of 30-foot-tall wall were built during the Trump administration, most of it in Arizona and New Mexico, blocking off vital wildlife corridors. (Learn more: Arizona’s border wall will include openings too small for many animals.)
“There are animals right there within just a few kilometers of the border that could easily be impeded from moving further north if the border becomes impermeable,” Koprowski says, due to extension of the border wall and expansion of highways.
“But more than anything, the [finding] provides great hope that this connectivity can be maintained,” he says—and even, possibly, improved.
The borderlands of Arizona and New Mexico, and its series of mountain ranges, known as Sky Islands, represent one of the most biodiverse areas of North America. Interspersed with mountains are the dry plains of the Sonoran and Chihuahuan Deserts and assorted grasslands and riparian areas, collectively home to tens of thousands of species of plants and animals. For eons, jaguars, mountain lions, ocelots, bears, and many other wide-ranging species have freely roamed across this contiguous biome. But barriers such as roads and fences now hamper this movement.
Nevertheless, in the last 25 years, at least seven jaguars have been seen in Arizona—including one still thought to live in a mountain range in the southeastern part of the state—and about the same number have been observed across the border in Mexico.
Moreover, a March 2021 study estimates that a huge swath of the region is prime jaguar habitat, and could likely support a population of a few hundred animals. Jaguars are classified as an endangered species in the United States.
Somewhere around 200 jaguars live in the Mexican state of Sonora, and both cats Marin observed were likely born somewhat close to Arizona, perhaps within 60 miles, says Gerardo Ceballos, a researcher with the National Autonomous University of Mexico.
Female jaguars generally do not venture very far from where they were born, and their mobility is the limiting factor to the species’ expansion. Males, however, can roam far and wide in search of territory and mates. The big cats face a variety of threats in Mexico, including poaching and retaliatory killings for their perceived role in livestock predation.
“If we continue trying to protect the jaguars, maybe within about five years we could see pregnant females in the United States,” Ceballos says.
But to move north, the cats need protected wildlife corridors. Any expansion of the border wall will further harm animals’ ability to move freely—and parts of the wall will need to be opened up to reduce the harm it has already caused, experts say. The Biden administration has pledged not to significantly expand the border wall, and some discussions are underway to lessen harm to wildlife, though no major changes have yet been made.
“Unfortunately, now the border wall represents a new barrier for jaguars to reach the United States,” says Antonio de la Torre, a biologist with the conservation group Jaguares de la Selva Maya, who studies the cats. “It is critical to implement a mitigation measure to solve this issue if we want to ensure the natural expansion of jaguars to the north.”
If you protect it, they will come
Until recently, much of what is now northern Sonora and southeastern Arizona had plentiful wetlands, known in Spanish as cienegas. That’s why Cuenca Los Ojos is working to bring water back to the landscape, and has so far restored about 75 acres of wetlands and streams, says Jeremiah Leibowitz, the organization’s executive director.
Prior to 2019, the 30 miles of Cuenca Los Ojos’s northern border, which abuts Arizona, had only short vehicle barriers and barbed wire fencing a few feet in height, which wildlife could easily cross. But now, it’s lined with 30-foot steel bollard walls, Leibowitz says. A few corridors remain devoid of such tall barriers, however, such as the southern end of the Peloncillo Mountains that straddle Arizona and New Mexico. (Learn more: An endangered wolf went in search of a mate. The border wall blocked him.)
This area, like much of its surroundings, receives half or more of its rainfall during the monsoon season, from June to September. After European colonization, people modified the landscape to be much less absorbent, replacing prairies with agriculture and building impermeable structures, including asphalt. As a result, this rain can run off the land quickly, causing erosion.
Cuenca reserve managers are working to restore the original permeability of the land, in part by slowing down the water with stone erosion-control structures, Leibowitz says. Beavers, whose dams also control water flow, have also recently recolonized many of the streams on the preserve. Both Sonoran jaguars have been seen near a stream on the reserve that runs year-round.
Establishing a range
Valerio and Bonito sometimes frequented the same area within a few days of each other, according to the camera trap data. As they’ve gotten bigger, Marin figured one would push out the other—upon reaching reproductive age, male jaguars try to establish their own territory.
Sure enough, Valerio, who is ever so slightly bigger, has stuck around—he was last seen in March—while Bonito has not been observed since October 22, 2021. Marin suspects he is somewhere nearby, but since the animals can range so widely, it’s anybody’s guess.
Besides looking for wildlife using cameras, Marin worked with biologists Melissa Merrick, Katie Benson, and Matt Valente to sample environmental DNA from some of the streams, which turned up evidence of jaguars, black bears, white-tailed deer, deer mice, and other local wildlife. The team hopes to expand their sampling and study of eDNA to learn more about the presence of terrestrial wildlife, a practice that remains in its infancy, Benson says.
In the meantime, the research shows the area is home to a bevy of important species, and that habitat restoration can increase an area’s biodiversity.
“The fact that the animals are using this area over and over again—all of that speaks to the quality of the habitat and the need to increase that connectivity” with surrounding areas of Mexico and the United States, Koprowski says.