It is useful to start at the end, which is also the beginning: at the far side of an imaginary bridge, picturing a mountain lion slinking over the rise to the east, hugging the shadows and contours of the easy-rolling ridge, then arriving at the 101 freeway’s eight lanes. Mountain lions have died here before, crossing from one sliver of wilderness to another—from the inland, semi-coastal ranges in the Angeles and Los Padres National Forests, across the Simi and San Fernando Valleys, to the Santa Monica Mountains, which run along the Pacific Ocean before elbowing eastward, inland again into the middle of Los Angeles. If the mountain lions don’t die crossing over, those moving westward into the Santa Monicas enter the home range of a famous and stressed-out cat family with a particularly famous son, whose likeness has been printed on magazine covers and T-shirts. The lions here are celebrated and beset upon by all sides—they’re cramped, which is why they are also so ill at ease. It was these cats, the famous group, we were trying to imagine finding a way eastward, over the freeway, escaping L.A.

The crossing point where the bridge might be is named, too perfectly, Liberty Canyon. It is not much of a canyon, more of a dry, narrow valley, or a choke point between a few large hills. We—biologists, ecologists, animal-corridor experts, a few scientists employed by the California Department of Transportation, and I—were here imagining mountain lions and the bridge that they might cross mostly because the bridge will be expensive—many tens of millions of dollars, certainly. It will also be the first of its kind: an overpass in the second largest urban area in America, constructed primarily for critters. Hikers, too, perhaps. Not building the bridge would eventually mean that the isolated population of famous lions roaming the hills of Malibu and Hollywood would collapse after so much inbreeding. This was what we were on the hill to weigh: the worth of an apex predator living alongside another apex predator, the apex of all apex predators, which is, of course, us.

Americans have been good at killing mountain lions for a long time, and still are. The minimum estimate is that 65,665 have been shot or poisoned or trapped or snared by bounty hunters, sport hunters, hunters paid by the federal government, state governments, and city governments from 1907 to 1978 throughout twelve states in the West. Mountain lions are still hunted for sport in Wyoming and South Dakota. But even left alone, mountain lions will live fast and hard and die in spectacular ways, often fighting one of their own, or drowning in irrigation canals, or suffering a fatal kick to the ribs from an elk or particularly brave mule deer, or breaking its back during a failed leap. In one instance, an old cat researchers had named Snaggletooth ran into a manzanita bush and a five-inch stop pierced its throat, after which it bled out in the sand. But Snaggletooth was getting old for a cat, pushing seven.

Today the US Department of Agriculture’s Wildlife Services (previously called the more ominous and accurate Animal Damage Control Department) kills some 200 mountain lions each year at a cost of about $30 million. The effect is at least questionable and almost certainly adverse. Kill a lion, and another one will move into its territory, this one younger, bolder, dumber, and more likely to take down livestock or approach humans. Mountain lions communicate through code: scrapes or scratches on tree bark, or piles of pine needles, leaves, and dirt gathered under a tree or along a ridge line, and sometimes peed or shit upon. Males leave far more of these scrapes or piles than females, who, like house cats, tend to bury their stool fastidiously. Males take up more room, too. The cats use the scratches and bodily fluids to locate and, mostly, avoid their own kind. Being cats, they rarely care for the company of others. They love edges, but especially the edges of environments—where the forest meets a clearing, where the mountain becomes a valley, where there is dense growth for them to hide and leap upon prey lingering in the open. Human landscapes—where clearings are small, growth is managed, and edges are everywhere—baffle them.

The hide of most cats is loose for their own protection, so that the inevitable cuts and scratches they suffer don’t reach anything vital. But the hide of a mountain lion is particularly loose, a size too big, because deep wounds go with the territory. Their hide, like so much else about them, has not adapted to protect them from humans. It wasn’t until 1963 that California declassified them as varmints. Before then, a hunter could expect a $50 to $60 payout for a pelt, plus expenses, which averaged between $500 and $600. The Massachusetts colony paid bounties for cougars beginning in 1742; Connecticut offered a twenty-shilling bounty per catamount beginning in 1684; in the 1500s, Jesuit priests in Southern California offered Native Americans a bull for every cougar killed. California began another official hunt for mountain lions in 1971, as a means of protecting a different sort of livestock: The state had just reintroduced bighorn sheep, at the cost of $2,500 per animal.

The state-sanctioned killing of mountain lions for the protection of another native species reminds me of a passage from a William Cronon essay, “The Trouble with Wilderness,” in which he argues that we are striving toward “the illusion that we can somehow wipe clean the slate of our past and return to the tabula rasa that supposedly existed before we began to leave our marks on the world.” Wilderness is a great idea. It’s also an impossible one. We cannot recover—let alone recreate—a state of nature that precedes the ways in which we’ve so radically altered it. The Liberty Canyon bridge was an acknowledgment of this impossibility, a piece of very human infrastructure manufactured for the benefit of a persistent but adulterated nature. We certainly aren’t going to move out of the mountain lions’ way; the concession is to build a path that allows it safer passage through our world.

As the group walked up the hills and downthe washes beside the freeway, we were startled at just how easily the mass of concrete and thrum of traffic disappeared—never completely, there was always some reminder, but nature, foregrounded, helped us forget exactly where we were. Tall grasses and wild mustard and gnarled oaks gave cover to doves and quail, bobcats and field mice. Then, coming up a rise, there was a tear in the land and the rumble of traffic again, reminding us: Here is the edge.

“No one even in Europe and Canada has tried to do what we’re trying to do,” Seth Riley had said before inviting me on this freeway walk. Riley is a wildlife ecologist at the National Park Service and is tasked with keeping tabs on the ten or fifteen mountain lions that live in the Santa Monica Mountains at any given time. The walk was near the tail end of a three-day workshop that had gathered together wildlife-crossing experts from all over the country to consider the isolated urban populations of cats in Los Angeles and another, even more isolated group of cats in Orange County. These populations, surrounded by cities and highways, are essentially marooned castaways on mountainous islands. If crossings aren’t built within the decade, many predict the complete disappearance of big cats from Orange County. The situation in the Santa Monica Mountains is almost as grim. Riley described the slow garroting of nature by the freeways, adding that all the time and effort and money spent to protect these mountains would have been for nothing if certain species couldn’t wander when and where they needed to.

A lion’s home range can be anywhere from twenty-five square miles to as much as 400, and is especially important to female mountain lions, which require familiar territory with consistent prey to raise and protect their young. These residents, as they are called, are still transients within their space; the wandering, impertinent nature of a mountain lion’s home within its home range is imprinted early. Just a few months after giving birth, a mother forces her litter out of their den (often just a small, well-hidden clearing), moving them somewhere else so they don’t feel overly attached to their birthplace. (As the biologist Kevin Hansen puts it, “they are not handicapped by the human compulsion to return to a single safe base at night.”) After several months, when they are big enough and strong enough, the kittens will leave their mother for days at a time to stalk prey. Soon afterward, she abandons them. In Southern California, where there is less room to roam, this abandonment is different. Knowing the time has come to part ways, but having nowhere to go that isn’t claimed by another cat or is, more likely, too close to humans, the mother begins to simply ignore her kittens, even appearing to act annoyed around them. Eventually, the juveniles get the picture and leave.

Survival for these transients is even more precarious than the difficult life of a resident cat. Transients are novices; they haven’t learned much about the ways of the human world. Often, when mountain lions appear among us, in a neighborhood or schoolyard or strip mall, they seem pathetically ill equipped to navigate the surroundings, and are run over or gunned down. These are almost always transients. Rather than duck back into the edges of things, the cats meander and linger—confused or panicked or claiming ownership over this strange new place. And sharing our spaces with animals capable of killing us is not something we intend to do. Which is why the bridge represents such a remarkable sea change in policy.

For more than fifty years, a patchwork of conservation groups—but especially the Santa Monica Mountains Conservancy—has been buying up and protecting land. It wasn’t until about ten years ago that Riley began working on the bridge, and not long before that that anyone paid much attention to where and how animals were moving between this patchwork of conserved land. Once they did, they noticed the one point where protected land met on either side of the freeway: Liberty Canyon.

When I pulled up to an old oak tree just past the off-ramp at Liberty, Riley was there, pacing. The group had been discussing the design and engineering of various types of crossings—including tunnels and an overpass—for a few days, and Riley was hoping to convince them to support the proposed bridge site. Going over the freeway, Riley said, would be better for more species. Deer, for example, hate tunnels, and rightly so, as larger prey animals tend to avoid areas where they cannot see from side to side, where an ambush might be imminent. There’s what’s known as an “openness ratio” to wildlife tunnels that necessitates widening the longer the tunnel might be, so that skittish creatures, like deer, can see the light at the end and feel safe in the middle. A tunnel under eight lanes of traffic—ten, including the shoulders—would be about 200 feet long and thirty-two feet wide, making it possibly as expensive as the overpass. Plus, the easiest way to build such a tunnel is what’s called “cut-and-cover,” meaning crews cut the freeway open, dig a trench, and cover it up. But along one of the busiest stretches in the world, such an endeavor would never work.

The bridge could be living. Out in the sunlight, lined with dirt, it could have plants, wildflowers, even trees. What would make the bridge truly unique among all constructed animal crossings is the urban density that would surround it. “There have been crossings built, but in places that aren’t urban at all, like Banff,” Riley said. “To have a bridge here … it would be an amazing statement.” When I asked Riley just what that statement might be, he paused, then said, “It’s about the value people are placing on wilderness, on living next to what is wild.”

The second-to-last site we saw was a pretty, densely overgrown wash, still wet with the morning’s fog off the Pacific, a trickle of runoff and the musty smell of sycamore. There was already a drain running under the freeway here, large enough for us to walk through but dank enough for no one to volunteer. A few of the scientists considered this an already viable option for crossings, particularly if the tunnel was widened. But it would be unseen, tucked away in the overgrowth, barely a statement at all. One of the Caltrans scientists mentioned the irony of looking for funding for this project. Most wildlife crossings come about to protect humans. Hit enough big critters, cause enough accidents, kill enough motorists, and suddenly the funds become available to steer various creatures (deer, mostly) off the roadways, saving lives both human and not. But no one other than the cats had been harmed after the crashes on the 101. The scientist smiled, or grimaced, at this, and so did I. Even in death, the big cats wouldn’t conform.

Mountain lions are difficult to see in the wild,even if you know exactly where they are, and especially if you’ve prepared yourself to see them. Riley’s partner at the Park Service, biologist Jeff Sikich, told me that during the day, hikers often pass within a few yards of mountain lions dozing in the chaparral. While tracking cats, Sikich has been able to locate exactly where they are by their radio collars, but is still unable to actually see them. The most famous of L.A.’s famous lions is a resident male named P-22 (“P” for puma; 22 because he’s the twenty-second mountain lion with a tracking collar, as part of the Park Service’s ongoing study of them in the Santa Monica Mountains). There are T-shirts featuring his profile, complete with radio collar and, printed below his visage, the word citizen. His exploits are tracked via several dedicated Twitter accounts, and when he holed up under a house in the Hollywood Hills, it was a major news event. Recently, P-22 entered the Los Angeles Zoo, in Griffith Park, his home ground, and killed a koala. The response was far more measured than when P-22 was under that house—a shrug, more or less. Cat’s gonna cat, zoo keepers said. That, and the zoo needed to do a better job protecting its charges from a big natural predator that lived nearby. Despite all this, sightings of P-22 have been rare. A friend of mine who lives up in the hills where P-22 roams was sipping coffee one morning and saw an odd-looking dog and realized, only after it was gone, that it was probably a cat; was probably P-22. I’ve been searching for mountain lions my whole life, trekking through their territory practically since I could walk. In all that time, I’ve spotted only two. One had died from rat poison and mange; the other was in a zoo—pacing, panting, and pinched.

Even in name, these cats are difficult to pin down. The mountain lion is said to have more names than any other animal. “Cougar” comes by way of Brazil’s Guarani Indians, from cuguacuarana, which was almost certainly their name for jaguar, and which French naturalist George Buffon adapted for a different American cat. “Puma” is rooted in the Incan language Quichua and means “a powerful animal.” The Cherokee called them tlv-da-tsi, or “Lord of the forest.” Chickasaws called them koe-ishto (or ko-icto), which translates, roughly, to “cat of God.” Cree called them katalgar, “greatest of wild hunters.” On the Puget Sound they were “fire cats,” carrying flames down from the mountains; in New Brunswick the Malachite called them pi-twal, “the long-tailed one.” French Canadians called them carcajou.*

In the American West the cats can go by “cougar” or “panther” or “puma” or “mountain lion”; in Appalachia they’re “panthers” or “painters”; in New England they’re “catamounts.” Linnaeus, father of taxonomy, called them Felis concolor: cat of one color. But even that name has changed to Puma concolor, to designate the uniqueness of the pumas among cats, which vary surprisingly little species to species. Pumas have rounded pupils, like cheetahs, but unlike cheetahs they may not purr (there’s some debate here, too, among biologists about whether mountain lions even purr). The first big book on cougars, from 1946, strikes at the nature of the animal in its title: The Puma: Mysterious American Cat.

We name things, in our uniquely human way, to tame them. A name brings about order and hierarchy; separation by means of participation. A mountain lion isn’t a lion, but it lives in the mountains, sometimes, but also, sometimes, not. It’s also a puma and a cougar and a panther. The lack of a single name for the mountain lion is the best, most fitting tribute for such a weird survivor. We couldn’t kill or tame the creature. We couldn’t even agree on a name.

Some days, particularly when it’s bright and quiet, in the region of Los Angeles called Mid- City, I walk south from my apartment to visit two of my favorite pieces of unintentional art, and think about how it is that mountain lions can still be here not quite with us but among us still. The first piece is an illuminated wall of dire wolf skulls. The other is a brass statue of a saber-toothed cat. Both are very close to but not a part of the Los Angeles County Museum of Art, which sits just across the park. Between them is a blackened pond: a tar lake. Throughout the park, bits of thick black mass ooze out of the earth, burbling with geological patience to the surface, breaking through the lawns and darkening large patches of the park’s lowlands, all the way to the art museum, which has gone to great lengths to fend off the indignity of the tar, which mucks up the earth and stinks up the air and creeps to within a stone’s throw of priceless canvases.

Another museum, the one that houses the dire wolf skulls, is named after George C. Page, a citrus magnate who built a fortune selling crates of oranges and the myth of California as the Golden Land. Part of this myth was that through sheer engineering and force of will man had saved Los Angeles from the desert, had made the dry land fertile. But the land here was never desert. It still isn’t, even though Angelenos are tearing up their lawns and replacing them with hard-packed decomposed granite and cactus gardens. The natural landscape is greener and grassier than most would believe—oak woodlands and sycamores along the arroyos, and shrubby, bushy, sage-scented chaparral up on the dry hilltops farther inland.

Saber-toothed cats prowled this lush landscape millennia ago, going extinct 10,000 years back, during the last ice age, along with the mammoths, the giant sloths, and larger panthers and leopards. There were also a variety of pygmy deer and antelope, all wiped out once man moved in. The mule deer that remained were bigger, the mountain lions smaller (the bobcats smaller still). The midsize cougar, living on the edge of things, could fit in with the human presence in the landscape, and did for a long while, revered and even relied upon by many tribes for the meat they left behind after a kill. Miguel Ordeñana, who coordinates citizen science at the Natural History Museum of Los Angeles, told me that, despite our endless attempts at killing them off, the public’s renewed fascination with mountain lions in Southern California has mostly to do with the cat’s ability to stick around. “As we become more aware of them, people feel guilty,” he said. “It’s a bold statement, to coexist with mountain lions. I think with this crossing,” he added, meaning the Liberty Canyon bridge, “people understand that it’s not just for the mountain lions, it’s for our effort to fix our mistakes.”

At the oak at the end of the off-ramp, where Seth Riley and the rest of us finished our morning walk, we came to a rise: a small trail cutting up through tall grass that led to a freeway overlook, where the road appeared as a gash between two semi-green hills going brown. We climbed the hill and thought about how to unmake the world, or make it wild again, which was, of course, impossible. So instead, we imagined a bridge—a gesture, an offering of peace and safe passage to the stubborn wild things that have hung on in spite of us.

* Soon after this essay was published, a couple of readers responded with a correction, clarifying that among French Canadians, carcajou is the common name of the glutton, or wolverine. A simple Google search will show that they’re right. So I went back to the books, and that, in turn, revealed a fascinating narrative etymological evolution.

In his 1793 Journal d’un voyage dans l’Amérique, Pierre François Xavier de Charlevoix wrote of “the Carcajou, or Quincajou, a Sort of wild Cat; whose Tail is so long, that it can twist it several Times round its Body; Its Hair is a reddish brown.” Wolverines have short tales; this wild cat was a cougar. The confusion was better illuminated by W.A. Perry, writing in 1890: “The French in the early settlement of Louisiana called it Cougar, and some of their naturalists, eager to make a little notoriety, gave it the name of Carcajou, which really belongs to the Glutton. Others called it by the outlandish, unpronounceable name of Gouazoura, and if they could have found a worse name they would doubtless have applied it to this much-named creature.” The old carcajou attachment to cougars continued right up into the 21st century—I found several books on the cats that listed it among its many historical names.

The story of how a name for one fierce and mysterious predator, the wolverine, might move to another is a story as old as language itself. I asked several linguists (even some French Canadians) for their thoughts on the carcajou confusion. One brought up the fact that this wasn’t the first case of the name for mountain lion getting lumped in with other bad beasts: in Montana Salish the name means “big coyote.” We’ve long lumped fearsome and mysterious predators, linguistically—like a blank spot on a map that reads “here be monsters.”

“My guess, and it’s the merest guess, is that carcajou was once used for both animals [wolverine and mountain lion] by people who weren’t all that familiar with either one,” the linguist Sarah Thomason wrote to me. She added that several of her sources seemed to link the word carcajou with kinkajou, but kinkajous are a kind of raccoon-like critter from South America, and carcajou most likely comes from Montagnais, an Algonquian language spoken in Canada. That the word might travel so far south and become attached to an arboreal raccoon seemed dubious, at best. Language is weird and slippery and plenty about its history is ultimately unknowable. The same could be said about cats.