"DAMN IT," CHRIS BUGBEE SAID. The batteries in his motion-activated trail camera were dead, and Bugbee, a wildlife ecologist, hadn't gotten as many photos as he had wanted for his wildlife census. That morning, he and I had driven 90 miles from Tucson to the Huachuca Mountains, rain lashing his truck as we snaked through Arizona's high-desert grasslands. After parking at a remote trailhead in the Coronado National Forest, we made a three-mile hike up a steep creek ravine, along the way passing some of the hugest piñon pines I've ever seen. When we got to the camera trap that he'd placed on a small tree trunk, we found that the camera had taken only seven photos before shutting down: two deer, one squirrel, one gray fox, one set of legs clearly belonging to a hiker, several sets of legs wearing the military-issue boots of the U.S. Border Patrol, and one frighteningly large puma. 

Most likely, cold had killed the batteries. Even though it was late March, the pines and firs on the slopes of the Huachuca Mountains were dusted with frost. There was no sign of what Bugbee and I weren't technically looking for but most fervently hoped to catch a glimpse of: the jaguar known to biologists as the Huachuca male, spotted in the rugged mountain range on the United States–Mexico border in December 2016.

In the last decade, a string of jaguar sightings in the American Southwest has electrified residents of Arizona and New Mexico and fascinated people worldwide. Normally, efforts to recover threatened species require a great deal of time, money, and human effort. Think of the reintroduction of the gray wolf, translocated from the Canadian Rockies to Yellowstone National Park in the mid-1990s and closely monitored by federal officials ever since. Or the California condor, nursed in captive-breeding programs until its numbers were large enough to return the bird to the mountains of Big Sur. The jaguar hasn't needed any of this. Moving northward from the foothills of Mexico's Sierra Madre, the species is reestablishing itself in some of the territory it once called home. "They are here, and they are trying to come back on their own," Bugbee said. "Without any help from us, they are coming back." 

Before meeting up with Bugbee, I had spent a few days backpacking alone through the Miller Peak Wilderness, a 20,000-acre preserve near where a trail camera located at Fort Huachuca—an army intelligence post—had captured a nighttime photo of the male jaguar. From what biologists had told me, there was a chance he was still in the area. 

I didn't have any romantic notions that I'd spot some sign of the jaguar, among the most elusive of midnight creepers. The Endangered Species Act outlaws any attempt to even track a listed animal. (Bugbee and his wife, Aletris Neils, have a wildlife-research organization called Conservation CATalyst, and they are allowed to set up trail cameras under Arizona Game and Fish Department regulations.) I just wanted to take the pulse of the place. As anyone who has spent time in wild areas knows, an apex predator changes the valence of a landscape, like salt added to a stew. To be in the company of predators, poet Gary Snyder once wrote, is "ecology on the level where it counts." 

Like other apex predators, the jaguar has become a symbol greater than itself, wrestled over by conservation groups, federal officials, state wildlife agencies, and academic researchers. Yet almost everyone—regardless of their take on how best to protect the jaguar—expresses awe over the species' tentative recolonization of the Southwest. Traveling through the borderlands, I heard people wonder again and again at the jaguar's return. 

Jaguar mural by Kati Astraeir, in Tucson, Arizona | Photo by Lisa Harris

"It just really does my heart good to see that this animal is making a living in the southwestern U.S.," Steve Spangle, the U.S. Fish and Wildlife Service's field supervisor for Arizona, said. Tanja Linton, the media relations officer for Fort Huachuca, described base residents' reaction this way: "Super stoked, super awesome. Just the rareness of it, the coolness of it." Randy Serraglio, the Southwest conservation advocate at the Center for Biological Diversity, told me, "Jaguars are, you know, they are just very sexy."

But awe alone isn't enough to recover a species. The return of the American jaguar, thrilling though it may be, is precarious. Roads and ranchettes interrupt migration routes between its mountain territories. A pair of proposed mines—a copper mine in the Santa Rita Mountains, a silver mine in the Patagonia Mountains—would obliterate prime habitat. Then there's President Donald Trump's proposed border wall. If it were ever completed, it would eliminate any future chance of jaguars migrating from Mexico. 

"Restoring the jaguar to the Southwest has the potential to be the conservation success story of the 21st century," Bugbee said. "We are at a major crossroads right now, especially with the border wall. We have to decide: Do we want our native big cat back or not?" 

A JAGUAR'S SPOTS ARE AS DISTINCT as human fingerprints. Biologists compared coat patterns to identify the seven different jaguars that have prowled the United States over the past 20 years. Jaguar spots were how wildlife officials were able to distinguish Macho A, the big cat that set off a camera trap in 2001, from the unnamed jaguar that a mountain-lion hunter treed in the Peloncillo Mountains five years earlier. They were how scientists knew Macho A from Macho B, who was killed in a botched attempt to radio-collar him, and how they've kept tabs on El Jefe (a.k.a. the Santa Rita male), the cat that Bugbee made famous with a 41-second video that went viral in March of last year. The jaguar's spots were how biologists knew that the cat caught last November on a Bureau of Land Management camera trap in the Dos Cabezas Mountains, 60 miles north of the border, wasn't El Jefe—and how they know that the Huachuca male is his own self and none of these others. 

Biologists say the jaguar (Panthera onca) is either a small big cat or a big small cat. Adult males typically weigh around 160 pounds, about the size of a large dog. Yet the jaguar possesses an outsize strength. A jaguar is squat, with short legs, a broad chest, and a cinder-block head. "Built like a fireplug," we'd say if it were human, the fullback of the Panthera genus. Its jaw is more proportionately powerful than any of the other roaring cats', the result, one biologist speculates, of having spent a critical phase of its evolution eating sea turtles on the Caribbean coast of Central America. The jaguar's signature kill method is to attack from above and twist the head of its prey to break its neck. The jaguar then crushes the prey's skull and eats the face and tongue, which it considers a delicacy. "The jaguar puts the animate world on edge," A. Starker Leopold, the son of Aldo Leopold, wrote while studying the big cats in northern Mexico in the mid-20th century.

The jaguar is also distinguished by its stealth. A lion cub will walk straight across a room toward its destination; a jaguar cub, in contrast, will lurk at the edges of a room, using whatever cover it can find. Even in places with significant jaguar populations, people rarely see them. Zookeepers say that, in comparison with other big cats, the jaguar is "unreliable" and "untamable." 

The Olmecs of Mexico—the foundational culture of Mesoamerica—built their religion around the jaguar. Shamans and medicine men were believed to be were-jaguars, and the Olmecs revered people with Down syndrome, who were thought to be the result of a sexual union between a woman and a jaguar. After the collapse of the Olmecs, jaguar veneration lived on with the Mayas and, later, the Aztecs, whose fearsome shock troops were called the Jaguar Knights. 

Mention the jaguar and most people imagine a jungle cat prowling the rainforests of the Amazon or the mountains of Central America. Today, most of the 60,000 or so wild jaguars in the world live in the tropics, but the animal's range once included what today is the United States. Biologists say that the jaguar likely roamed a territory that stretched from Los Angeles to New Orleans. Well into the 19th century, the animal was not uncommon in the West. Sam Houston, the founder of the Republic of Texas, had a jaguar-skin vest that was among his prized possessions. The Comanches of the lower plains liked to use its pelt to cover their arrow quivers.

The jaguar's extirpation came at the hands of the usual culprits: habitat loss from logging, mining, and cattle grazing; sport hunting and persecution by ranchers; and the decades-long, U.S.-government-funded campaign to wipe out predators of any kind. For a while, jaguars held on in the jagged uplands of Arizona. The last known female was shot in 1963 at Big Lake in the White Mountains, a subalpine conifer forest 175 miles north of the Mexico border. 

The U.S.-Mexico border fence highlighted by Border Patrol headlights in Sasabe, Arizona. | Photo by Matt Nager

The areas that the jaguars roam today are known as the Sky Islands. These are a chain of some 40 distinct mountain ranges that stretch from the Mogollon Rim of Arizona and New Mexico southward, across the international boundary to the upper reaches of the Sierra Madre. The Sky Islands are an archipelago of vibrant forests amid a sea of desert. From the summit heights, it feels like you're floating on a waterless ocean. From the desert plains, the Sky Islands look like another world entirely—green-clad, snowcapped cloud magnets. 

The Sky Islands are still a harsh and arid environment, but the extremities of the desert are tempered by elevation. Agave-dotted grasslands give way to Gambel oak and dogged juniper, which fade into slopes of Mexican piñon and rise to heights covered in ponderosa pine, white fir, and aspen. The Sky Islands are an ecotone, a liminal space between the Sonoran and Chihuahuan Deserts and the junction of the southern Rockies and the Sierra Madre. 

The islands exist as a pathway, and a refuge, for migratory birds and animals. The Coronado National Forest, which encompasses most of Arizona's Sky Islands, is a biodiversity hot spot and contains more threatened or endangered species than any other U.S. national forest. Some 500 bird species—about half of all the bird species found in North America—have been reported in the region. Backpacking through the Miller Peak Wilderness, I saw plenty of sign of gray fox and black bear. At dawn, the desert forest was so full of birdsong that I thought I had awoken in a jungle. 

"The biodiversity of this region can be explained just looking at what regions we are connecting," Sergio Avila, a conservation research scientist at the Arizona-Sonora Desert Museum, told me. Born in the Mexican city of Zacatecas and now a U.S. citizen, Avila is wiry and intense, with a black ponytail and a knack for turning statistics into sound bites. "We have a lot of animals that move through these corridors, and that's the case of the jaguar and the ocelot, and the Mexican gray wolf, and, historically, the grizzly bear." 

The handful of jaguars in the United States have come from the Mexican state of Sonora, where there's an estimated population of 120, many living in or near a protected area called the Northern Jaguar Reserve (even as the jaguar was extirpated from the United States, it maintained a toehold in northern Mexico due to fewer human pressures there). Jaguars, like other big cats, are intensely territorial. When the cubs reach about two years old, the males leave their mother's home territory to carve out their own range. If there's already a dominant male in the area, adolescents are forced to disperse to avoid having to fight for turf. Some of those wandering jaguars have hopscotched from one Sky Island to the next until, unbeknownst to them, they have crossed a politically charged boundary. 

Of course, had there been a continuous, unbroken border wall like the one that Trump envisions, the jaguar's roaming would have stopped right there. 

"A barrier would block corridors. It would block valleys and block corridors from lower elevations to higher elevations," Avila said. "It's like you're used to waking up and going from your room to your kitchen, and then imagine that one morning you don't get access to your kitchen."

CHRIS BUGBEE HAD SET UP three wildlife cameras, so after the bust with the first, we kept going. With a bitter-cold wind coming from the plains far below, Bugbee and I headed northward. (To protect the jaguar from people who may wish it harm, Bugbee and I agreed that I would keep geographic details vague.)

In front of us, on a long leash, was Bugbee's tracking dog, Mayke. A caramel-colored Belgian Malinois, Mayke had flunked out of a Border Patrol drug-detection program. Bugbee adopted her while working as a field technician on the University of Arizona's jaguar study project and trained her to detect jaguar and ocelot scat. Mayke had been Bugbee's key partner during the time he monitored El Jefe for the university's project. Together, they captured dozens of pictures of the Santa Rita male for the university's research as well as the daytime video footage that, after he left the project, Bugbee released in collaboration with the Center for Biological Diversity. 

Jaguar territory in the southern United States and northern Mexico | Map by Steve Stankiewicz

The footage of El Jefe was seen by as many as 100 million people, and it made the animal a star. A local brewery called Barrio Brewing Co. named a craft beer after him (the Santa Rita Jefeweizen), and a giant mural was painted in downtown Tucson in his honor. But within the small community of people focused on jaguar conservation, the video sparked controversy, with some people fearing the footage could draw hunters to the area. As we hiked through the pines, Bugbee—who gets Boy Scout–earnest when talking about jaguars—said he had no regrets about releasing the footage, even though it had complicated his and his wife's dealings with the university. 

"I had a very close relationship with El Jefe—I wouldn't have done anything to endanger him," Bugbee said. El Jefe hadn't been seen for months when he released the footage, and Bugbee and other biologists believed he had split for Mexico.

We arrived at a meadow. Bugbee unlocked his camera from the trunk of a tree while keeping an eye on Mayke; during a previous visit to the Huachucas, she had treed a mountain lion, which sliced her face and left a long scar beneath her right eye. Bugbee checked the camera display.

The news wasn't good. The high winds on the mountain ridge had bent the tall grasses of the meadow so often that they kept triggering the camera's motion sensor. The photo scroll was monotonous: meadow meadow meadow meadow meadow. Every 40 images or so, there was something that was not grass. Deer. A bird, blurred by the motion of flight. Packs of coatis, a raccoon-like character with a long snout and a long tail. No jaguar. 

FROM THE SUMMIT OF MILLER PEAK, the spine of the Huachuca Mountains tapers to Yaqui Ridge. There's a parking lot at the Montezuma Pass trailhead, and from there it's an easy two-mile hike to Mexico. On the morning I set out backpacking, the trailhead was busy with Border Patrol activity: a half dozen agents preparing to make their rounds, a pair of heavy-duty trucks mounted with rotating surveillance dishes. 

Before heading up Miller Peak, I made the short detour to the border, hiking past stands of cholla pregnant with yellow buds. After about 40 minutes, I came to a barbed-wire fence and a five-foot-high, silver-painted obelisk that read, "Boundary of the United States/Treaty of 1853/Re-Established by Treaties of 1882-1889." The wires were spread apart, making a passage sufficient for a big cat, or a clutch of humans. On the north side of the fence, there was tall grass and cacti; on the south side, tall grass and cacti. Canyon towhees flitted back and forth. 

President Trump's talk about building a "big, beautiful wall" from the Pacific Ocean to the Gulf of Mexico obscures the fact that about a third of the southern border is already bisected by barriers. From the southern foothills of the Huachucas, I was able to see the various types of border-security infrastructure currently in place. To the east of Yaqui Ridge lies the San Pedro River valley. The green curve of the river is split by a plumb-straight, rust-colored fence, 20 feet high and made out of bollards—steel columns set close enough together to prevent passage but far enough apart that the Border Patrol can see what's happening on the Mexican side. To the west of Yaqui Ridge lies the San Rafael Valley. There, the border is guarded by what are called "Normandy barriers," named for the type of obstacles the German army set up on the beaches of northern France during World War II. Normandy barriers are designed to block vehicles but leave room for anyone traveling on foot to hop over or crawl under. 

The Arizona-Mexico border is 372 miles long. Of that, 123 miles are guarded by bollard fences, and 189 miles have Normandy barriers or other types of vehicular obstacles. The remaining 60 miles is land that is either too steep or too rugged for easy construction. 

Environmental groups such as the Sierra Club and the Center for Biological Diversity—along with many wildlife biologists—say that the existing border infrastructure is already causing significant harm to desert ecosystems. "What's going on at the border is more than just the wall," Avila told me. "It's the roads, the access roads, the helipads, forward operating bases, all of that. When we talk about the environmental impacts of the border wall, we have to talk about all of those things." 

In 2005, with the September 11 terrorist attacks still fresh in the public mind, President George W. Bush signed a homeland-security measure called the Real ID Act. Among other things, the Real ID Act gave the secretary of homeland security the power to waive any federal laws—including the Clean Air Act, the Clean Water Act, and the Endangered Species Act—if they are found to be in conflict with border security. So when border construction threatens the habitats of species ranging from the pygmy owl to pronghorn to bighorn sheep—or when contractors building a new segment of wall through the San Bernardino National Wildlife Refuge spill concrete into the river habitat of one of the country's few populations of Yaqui catfish and Chiricahua leopard frogs—there's little recourse. The Border Patrol has built roads through designated wilderness areas and has been spotted tearing across the desert landscape in Organ Pipe Cactus National Monument. Surveillance towers can disorient bats with their radar and their lights. (See "Collateral Damage," below, for more on at-risk border species.) 

Public lands like the San Pedro Riparian National Conservation Area and Coronado National Memorial are kept wild thanks to federal laws. But when the Real ID Act came along, said Dan Millis, coordinator of the Sierra Club's Borderlands program, "federal law goes out the window, and here come the bulldozers."

Although the wall was the original sail powering Trump's political ascent, the idea has run into headwinds since he took office. Democrats in Congress have pledged to do everything they can to stop wall construction, and lawsuits have already been filed. During spring budget negotiations, Trump was just barely able to get enough money to invite contractors to begin building wall prototypes, now under construction in California. Not a single U.S. representative from a border district—Republican or Democrat—is in favor of the border wall. 

While environmental groups are unanimous in their disdain for the wall, the border militarization has, in one strange irony, benefited jaguar conservation. In 2010, the Department of Homeland Security granted several million dollars to the Fish and Wildlife Service for environmental mitigation to offset damage caused by border security. That money funded the University of Arizona's jaguar study program, including the placement of 300 remote wildlife cameras—the same cameras that made El Jefe famous. 

The frequency of jaguar sightings since the cameras were deployed raises intriguing questions: Are we seeing an increase in jaguars in the United States, perhaps as a result of climate change driving them northward? Or did the cameras just show a population that was here all along? 

Avila believes that the jaguars never left, and that their "comeback" is actually a case of new technology being employed by scientists and environmentalists intent on studying a fragmented landscape. Thanks in part to border militarization, there are more eyes on the landscape than ever before. 

A jaguar roams the 55,000-acre Northern Jaguar Reserve and surrounding Viviendo con Felinos ranches, 125 miles south of the U.S.-Mexico border. | Photo courtesy of the Northern Jaguar Project/Naturalia

IN DECEMBER 2016, less than three weeks after the first sighting of the Huachuca male, the Fish and Wildlife Service released its Jaguar Draft Recovery Plan. The document, some five years and 500 pages in the making, concluded that, since none of the jaguars captured on camera seemed to be female, conserving the population of jaguars north of the border should be a secondary concern to protecting jaguars in Mexico. Conservation groups complained that the plan ignored the possibility of introducing female jaguars into the United States, similar to what was done successfully with gray wolf reintroduction. In addition, the designated critical habitat boundaries failed to include territory more than 6,000 feet above sea level or north of Interstate 10, even though the female jaguar killed in 1963 was 2,000 feet above and 100 miles north of those lines. For a plan crafted by a U.S. agency, it put most of the responsibility for jaguar conservation on Mexico while putting little emphasis on north-of-the-border conservation tactics, like building wildlife-friendly road crossings. 

The jaguar recovery plan also contained surprisingly few mentions of the border wall. While it noted that "trans-border connectivity . . . is an important component of jaguar recovery," it did not discuss the fact that a future border wall would slice across five of the agency's six critical habitat areas. Conservation groups—already annoyed that they'd had to sue the Feds to develop the plan in the first place—were unimpressed. Defenders of Wildlife said the plan "would do little to recover the jaguar in the United States." The Center for Biological Diversity blasted the agency for concocting an "extravagant and ultimately Sisyphean project." 

In response to these criticisms, Spangle, from the Fish and Wildlife Service, told me, "We focused on the most important areas, and I think we did it right. We are going to put what few eggs we have in the area where the jaguars are breeding, which is in Mexico." When I asked Spangle about the border wall, he directed me to the agency's formal statement, which says the USFWS won't offer an official opinion on the wall until other federal agencies or Congress asks it to do so. 

According to the Center for Biological Diversity's Serraglio, the plan dismisses the need to give the jaguar as much range as possible so that the north can serve as an escape route should conditions become less hospitable in the south. "Real recovery, under the Endangered Species Act, is not just increasing the number of individuals of a species. It's also increasing the number of places where they can be found on the landscape," Serraglio said. "We need to allow the population to expand geographically as well as numerically."

What is true for other endangered species is also true for the jaguar: There is no recovery without connectivity. By cleaving the landscape in two, the border wall would violate a core axiom of wildlife conservation and foreclose any future for the American jaguar. Separation is how an animal goes extinct—first its population gets fragmented, then it winks out. The wall would, for the first time, make the Sky Islands truly isolated from one another.

BUGBEE'S LAST CAMERA WAS SOUTH of us on the mountain ridge. The sun had melted the frost in the treetops, and I could spot the spring blooms on the white firs—little puffs of pink on every branch tip. We marched a couple of miles until we reached the spot: a crook in the trail where a notch in the cliff face drained the heights, forming a seasonal seep. Nearby was a pine just the right width for a camera rig. 

Bugbee started to scroll through the images. The scenes were mostly the same as on the other two cameras: squirrel, fox, coati, deer. As he raced through, I tried to spot myself, having passed this very place while exploring the wilderness. Instead, the camera viewfinder filled with a massive mountain lion walking the trail just after dawn. "That's a big tom," Bugbee said, clearly impressed. I looked at the date and time. The lion had passed the place a scant eight hours before I had.

Bugbee kept scrolling. Squirrel, fox, deer. Then Bugbee's thumb stopped. There he was: the Huachuca male. 

The image was captured late at night, but the animal was unmistakable. A long, orange cat, its spots blending into the darkness. I could see how its ears were cocked in rigid attention. I could see the way those short jaguar legs kept it close to the ground. I could see snow wreathing the rocks. There was an audacity in how ordinary it all looked. This wasn't a myth or a relic—just an animal going about its business. I thought about my conversation with Avila the day before: The cameras on the land are making visible things that used to pass unseen. 

A few months later, back home in California, I got to see some more photos. In May, the Fish and Wildlife Service and the University of Arizona released a batch of Huachuca male pictures, the first made public since the animal was initially spotted. Looking at the photos online, I immediately noticed that four of the six photos were taken in daylight. This wasn't an animal slinking about. This was an animal comfortable in its territory. A migrant, maybe, a solitary wanderer, but one that had begun to make a home for itself in the United States. 

Then the time stamp on the two nighttime photos caught my attention—March 26. That was the very day I awoke on the slope of the Huachucas and marveled at a desert forest packed with birdsong. 

I felt a shock of recognition: The jaguar had been there all along.

COLLATERAL DAMAGE

The jaguar isn't the only animal threatened by President Donald Trump's proposed border wall. According to the U.S. Fish and Wildlife Service, an impenetrable wall would "potentially impact" 111 endangered species and some 108 migratory bird species. Here are just some of the ones impacted by border militarization. 

Ocelot: Known as the dwarf jaguar, the ocelot is about the size of a bobcat, with a jaguar-like coat pattern. Five ocelots have been detected in southern Arizona in recent years. Like the jaguar, they are migrating into the United States from Mexico, and a wall would halt their northward dispersal.

Cactus ferruginous pygmy owl: As its name suggests, the pygmy owl is tiny (barely seven inches tall), and it rarely flies more than five feet off the ground. The Border Patrol's fencing is already disturbing the owl's migration.

Mexican gray wolf: A smaller subspecies of the gray wolf, the lobo, is listed as endangered, with a scant 100 wild animals living in Arizona and New Mexico and just several dozen in Sonora and Chihuahua. A border wall would eliminate any chance of the two populations connecting and preserving genetic diversity. 

Pronghorn: The fastest land mammal in North America should have no problem navigating the Normandy barriers that stretch across much of the border. But the animal is notoriously skittish, and biologists worry that the Border Patrol's road building and frequent SUV and ATV patrols are disturbing its habitat.

Chiricahua leopard frog: Like a bullfrog but with spots, this subspecies has already lost 90 percent of its range due to human development. The construction of border-security infrastructure impacts the desert riparian areas where it thrives.

Bison: The national mammal of the United States once inhabited the grasslands of the Chihuahuan Desert. Today, a small remnant herd roams the New Mexico borderlands. Some animals have been spotted trying to climb over border fencing to get to forage and water.  

This article appeared in the September/October 2017 edition with the headline "Migrants."