Why Does The Puma Cross The Road?

The instinct to roam is key to the mountain lion's evolutionary success. Conservationists hope a wildlife crossing under Highway 17 will make the journey less deadly.

by Brendan Bane

Nov. 11, 2014—It’s a foggy autumn evening in the Santa Cruz Mountains. Cars glide through the low-lying mist and along the damp pavement of Highway 17. The roads seem void of life. But something is lurking in the darkness: a pair of glowing gold eyes that reflect every pair of passing headlights. They belong to North America’s largest feline, the adult male mountain lion.

The cat turns from the highway, venturing instead into the forest’s shadows. He can’t stop. He has ground to cover. As with other males of his species, his territory could span up to 200 square miles, and he’s evolved to aggressively defend every inch of it. This itinerancy, this need to move from place to place, evolved many thousands of years ago. Today, it puts the cats of the Santa Cruz Mountains in a precarious position: They keep getting hit by cars.

The evolutionary pressure to roam applies equally to many creatures, from mountain lions to dandelions. Sure, one is a 130-pound predator capable of crushing a deer’s windpipe in its jaws, and the other is a plant whose flowers we blow into the breeze for a wish. But in the light of evolution, both mountain lions and dandelions are dispersers.

When a dandelion spreads its seeds, the dry florets take to the wind and, if successful, colonize patches of land with available resources such as sunlight, water and open soil. When mountain lions reach about two years of age, they too float away from home to wander in search of unclaimed resources. Flower and lion—they are both driven by the same evolutionary constraint: the resources in their birthing places are already taken by others of their species—their parents—so they must disperse to find new ones.

Dandelions are not shot for trespassing, they are not battered by speeding cars and they were never systematically hunted under state-sanctioned bounty (puma-hunting in California was officially banned only 24 years ago). But today’s mountain lions are still dispersing away from their mothers and into the lethal obstacle course of the human-built environment, which sometimes ends in their staring down speeding headlights or the barrel of a gun.

The danger is worse for young males than for their female littermates. Female territories sometimes overlap and can fall within male territories, whereas adult male pumas have been known to kill same-sex trespassers. In recorded car-puma collisions, the victims are usually male.

Scientists are working hard to help the troubled cats, though. By studying their behavior and connecting preserved but discontinuous habitats, local researchers and conservationists aspire to forge sustainable relationships between the people of the Santa Cruz Mountains and the pumas they share space with. Their solution may lie just on the horizon and beneath the very highway on which so many mountain lions have died.

Creatures of Instinct

Those scientists have their work cut out for them. News from the cats’ PR department could be better. A male puma mauled a little boy near a Cupertino winery in September. The boy was released from the hospital with minor injuries the next day, but the animal was tracked down and shot later in the week.

“As far as we know,” says spokesperson Kirsten Macintyre of the California Department of Fish and Wildlife, “this was its first interaction with humans.”

As news reports accumulated, journalists reached out to experts to comment on the attack. When they contacted the Santa Cruz Puma Project, a UCSC-based research group that studies mountain lions using GPS-tracking collars, many of those reporters spoke with graduate student Veronica Yovovich.

“It must have been scary for both the little boy who was attacked as well as his family,” says Yovovich, who studies the intricate relationships between pumas, deer and plant communities. “It sounds like they handled the situation perfectly and were able to scare the puma away.”

The attack drew much attention, but such incidents are infrequent. To help put it into perspective, Yovovich recounts an instance in which she witnessed two hikers nearly meet a fate worse than any mountain lion attack.

She was teaching a course in large mammal conservation at Yellowstone National Park. As she and her students were resting on a lakeside knoll, a mother grizzly and her cubs emerged from the woods to forage by the water’s edge. The bears, divided only a short distance by a hiking trail, were far enough from the group for everyone to calmly enjoy the scene. Things turned from serene to alarming, though, when two hikers came walking down the trail.

“They were about to do exactly what we told our students never to do,” says Yovovich, “walk directly between a mother bear and her cubs.” She and her students yelled and waved to the hikers, but unable to see the massive grizzly and her cubs, they shrugged off the warnings and continued walking toward the bears.

There was no attack. The couple passed through the area unaware of how close they’d come to danger. The unseen bears rejoined and retreated into the woods moments after.

Yovovich’s story could have been about great white sharks swimming beneath surfers’ feet or hikers walking past secluded mountain lions, and it would have conveyed the same point. “You have no idea how many times you’ve been in mountain lion country,” says Yovovich, “and you pass right under one sleeping in a tree.”

Consider the 2 million annual visitors to parks of the Mid-Peninsula Regional Open Space District, a property that spans hundreds of acres of mountain lion habitat and includes the park where the mauling occurred. That’s 2 million people walking and biking near mountain lions each year. Then consider the fact that, until September, more than 100 years had passed since the last attack in that area, and the rarity of such an event becomes staggeringly apparent.

Biology and Tragedy

Statistics aside, people and pumas do, nonviolently, cross paths. Just this year, another young male, named 46M by the Puma Project, dispersed from his mother’s territory and into a parking garage in downtown Mountain View. Biologists from the Puma Project and Fish and Wildlife soon captured and relocated 46M, but not before he spent nine daylight hours hiding behind a bush in front of an apartment complex. Scores of people likely passed him on the sidewalk.

Although 46M was released back into the mountains, his subsequent journey did not end well. He walked along Highway 280 for the next few months, searching for a territory of his own. He hunted deer between patches of development, evading detection until, just a month ago, 46M attempted to cross the highway.

“His body was pretty messed up when we found him,” Yovovich says. “He was probably hit multiple times.” 46M had long been dead by the time Yovovich and her colleagues retrieved samples from his tissues.

He was far from the first to meet this fate. Just a year earlier, another young male known as 39M, made famous after falling into an aqueduct in downtown Santa Cruz, was struck and killed at Vine Hill Road. Fish and Wildlife had just implemented a new policy encouraging nonlethal capture of mountain lions. He was the first big cat to be sedated instead of shot under the new rule, though he would die at human hands just five months later.

Anyone can see the misfortune in such animals being mangled by cars. But what’s easy to miss are the ecological ripples that emanate in the wake of their deaths. Killing a single mountain lion can lead to the deaths of multiple mountain lions.

Imagine that a male sires a few kittens. Those kittens and their mother are safe in his territory. Then imagine that male dies while patrolling, perhaps getting hit by a car. With the territory open, a new, younger male moves in. He adopts the land, the female and her offspring. But it’s poor strategy to squander resources on kittens that aren’t his own. So he kills them. It’s a sordid fact, but it’s also a rewarding strategy in terms of natural selection. The female returns to heat faster that way, and he’ll sooner have his own kittens. Similarly, a battered female puma may leave behind orphaned kittens. A single death can spark a brutal chain reaction; one car or bullet can lead to several dead lions.

Another common cause of death for mountain lions is gunfire. Consider 16M, popularly known as Atlas.

In April of last year, Atlas had established his own territory at Laurel Curve, which was flanked by Highway 17. A rival male’s territory lay on the other side of the pavement. When the neighboring male was shot for killing livestock, Atlas expanded his territory to engulf the vacant real estate, highway and all. He crossed the road more than 30 times in four months, and even survived being struck by a car. But he took up the same livestock-hunting habit and died the same way the previous male did.

Farmers that shoot mountain lions, which they are often able to do legally through a state-issued depredation permit, may believe they’re solving a problem by ridding their property of a problem animal, but it can easily make their lives more difficult. By killing older, wiser males, livestock owners pave the way for younger, more troublesome males to move in.

“Let’s say you have livestock,” says Yovovich. “You’re much more likely to have problems with a naive lion than an older, established male that has learned to stay out of the way. When you shoot the older, resident male, you get these young knuckleheads coming in.”

Young males may be more prone to risky behaviors because they haven’t learned their limits, a factor that could have contributed to the Cupertino attack.

Speeding cars, frustrated landowners and rival males all stand in the way of dispersing males. Consider also that puma populations in Northern California may already suffer from low genetic diversity, an issue exacerbated by highways boxing in the animals’ ranges, and it’s clear that pressure is mounting.

But a release valve could come in the form of a hole in the highway: a wildlife corridor that connects the preserved lands fragmented by Highway 17. The corridor is the product of collective efforts between engineers at Caltrans, conservationists at the Land Trust of Santa Cruz County and a pair of hopeful ecologists.

Save The Males

“Yellow spots are deer. Red stars are mountain lions,” says ecologist Tanya Diamond, who stands beside Ahiga Snyder while pointing to a map of the Santa Cruz Mountains. Together the two form Pathways for Wildlife, a research organization that uses motion-detecting cameras and GIS-modeling to monitor wildlife traffic.

Colored shapes pop out amid their map’s topography. Yellow spots and red stars cluster at two areas along Highway 17; they mark animal traffic hotspots where creatures have died trying to cross. “The roadkill data is very telling,” says Diamond, “because it shows us where the animals are attempting to cross and not making it.”

Earlier this year, Pathways for Wildlife and the Land Trust collaborated to find the best place for a corridor along Highway 17. Their records, along with GPS data from the Puma Project and reports from California Highway Patrol, showed that 13 mountain lions, mostly males, were struck and killed on the highway since 2007. Many more deer (easily one a week), bobcats, foxes and other animals have also died on the highway. In Santa Cruz County, most of the traffic is focused in the middle of Laurel Curve.

Drive along Highway 17 and it’s easy to miss this stretch of road. Visually, Laurel Curve doesn’t stand out from any other segment of the highway. But because of its heavy animal foot traffic and low development, the area bears great ecological significance. Four of the Puma Project’s study animals have crossed Laurel Curve seven times since 2008. Three were hit by cars. [Editor's note: the figures in the two preceding sentences were corrected on Nov. 12, 2014.]

On one side of the highway lies a 10-acre parcel, the Mansion Property, purchased and protected by the Land Trust earlier this year. Below it and sprawling to the other side of the road are 280 acres of unprotected mountain lion habitat known as the McDougal Foundation property. The nonprofit plans to raise $1 million by the end of this year so it can purchase the larger parcel and pave the way for Caltrans to build a large box culvert beneath the highway.

“For me, it’s not really about mountain lions,” says Dan Madeiros, the project’s manager at Land Trust. “For me, it’s about the ecosystem functioning correctly.” In 2011, Land Trust launched a 25-year conservation program tailored for Santa Cruz County. The organization plans to secure 50,000 acres of land to be preserved, played in and sustainably managed. Land Trust has since acquired one-fifth of its prospective acreage and is working to clinch another 190 acres near Laurel Curve.

Without a corridor, though, no animals can move between the areas. “We’ve made great strides with our past land acquisition,” Madeiros says, “but without those areas being connected, the ecosystem can’t function. Without corridors, those pieces are like isolated islands. They need to be connected.”

Tanya Diamond concurs, adding that once Highway 17 is made permeable to wildlife, habitats for dispersing mountain lions will open up. “There’s a lot of good habitat in the Santa Cruz Mountains,” says Diamond, “but a lot of it is already taken. It’s like getting a really nice apartment in Los Gatos or Santana Row. All the good stuff is taken up.”

Casualty of The Road

Less than a mile from Laurel Curve, Diamond and Ahiga Snyder are reviewing the footage from their motion-detecting cameras. Snyder climbs a ladder to unstrap one of their devices from a redwood and pops the case open. He removes the memory card and inserts it into his laptop. A window opens on the screen. They start watching clips. The first is of Snyder walking away. Then it’s nighttime and the footage goes to night vision. Some deer show up. Then a bobcat walks by. The two ecologists playfully discuss the animals they’ve seen so many times before, when suddenly, their chatter is broken by happy cheering. The last clip showed exactly what they hoped to see: a large adult male sauntering past the camera.

“If this is an older resident male patrolling the area and he’s wise to the highway,” says Snyder, “then when he mates and has offspring, by the time three or five years pass, and if there’s a culvert here, their kittens will be able to disperse and spread their genes.”

But they never will.

Diamond and Snyder’s hopeful male, referred to as “the McDougal mountain lion” because of the property he patrols, first started walking past their cameras in June of this year. He popped up every couple of weeks while faithfully guarding his circuit. On Nov. 6, he was struck and killed at Laurel Curve. The two ecologists thought he may have regarded the highway as a territorial boundary, but his actions proved otherwise when he tried to cross on that foggy autumn evening.

Perhaps it was because of the female on the other side of the highway, who had also shown up on the footage. “Our camera traps showed both lions walking toward the future site of the tunnel from opposite sides of the highway,” the Land Trust playfully wrote on Oct. 30, just a week before the accident. “Star-crossed lovers, meant to be, and the universe just says ‘no.’”

Indeed, the universe sealed its decision when the McDougal mountain lion perished just as many pumas before him have. With each of their bodies goes genetic diversity and secrets never to be deciphered by inquisitive scientists.

“Sadly, history is repeating itself,” Medeiros said later in a press release. “This wasn’t the first time a mountain lion was killed in the vicinity of Laurel Curve, but we hope it will be the last.” If his group can raise the remainder of its $1 million by Dec. 31, and Caltrans secures funding shortly after, animals could start walking beneath the highway as soon as 2020.

Though the pumas that have passed are gone forever, nature is resilient, and new cats will soon roam the forests. The scientists of the Puma Project recently tagged two new lions: 49M and 50M, both male kittens. In a little over a year’s time, 49M and 50M will be old enough to disperse from their mother’s territory in search of land to call their own. If the stewards of the Santa Cruz Mountains are successful, they may just have a way to get there.

To learn more about or donate to the wildlife crossing campaign, visit the Land Trust of Santa Cruz County website.

Mountain Lion Crossing
Wildlife Crossings: Good for Deer, Too
Troubling Pa Prints

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