Tracking Mountain Lions in California's Urban Jungles

Scientists struggle to track the secretive predators, which are turning up near cities' expanding edges, including around San Francisco Bay.

Crouched in the darkness, two field technicians squint at a laptop, hoping to catch a glimpse of California's most elusive predator.

"Possum. Possum. Possum," Richard Pickens says, flipping through photos. "Oh—fox."

Pickens is studying images from a camera stashed a few miles east of San Jose, California, among bay trees and meadows of thistle and stinging nettle. Scientists guess that about a half dozen adult mountain lions, also called pumas or cougars, prowl these hills. But tonight, the golden animals are living up to one of their many nicknames and slipping through the forest like true ghost cats. (Read about cougars in National Geographic magazine.)

That isn't always the case. As California's concrete jungles creep continually outward, more and more cats are finding themselves living on the edges of urban areas. Occasionally, they end up right in the middle of cities, like the mountain lion that wandered into downtown Mountain View earlier this year, and the Hollywood puma that lives in Los Angeles.

Those situations are rare, and often end badly for the cats—the Mountain View cat was later killed by a car, the Hollywood puma suffered from rodenticide exposure—but the long-term effects of urbanization are much more insidious. Penned in by freeways and suburbs, local puma populations can be cut off from others. Isolated populations lose the ebb and flow of genes needed to keep groups healthy.

This is why Pickens and his colleague, Ian Hanley, are in these hills. They're working with the Bay Area Puma Project, using GPS collars and cameras to track pumas' movements near one of the largest metropolitan areas in the country. Scientists at the Bay Area Puma Project are hoping to learn everything they can about these cats: what they eat, when they mate, where they go-and how they die. These are the kinds of observations that can most effectively inform conservation efforts like setting aside useful tracts of land for wildlife.

"Pumas are magnificent, graceful, quintessential ingredients in a wild landscape that is becoming less wild every day," says Zara McDonald, president of the Felidae Conservation Fund, which operates the Bay Area Puma Project.

Golden State, Golden Predator

Solitary and stealthy, pumas live in roughly half the state. As top predators, they keep ecosystems balanced; scientists suspect pumas help regulate everything from deer (their favorite meal) to coyotes to grass cover to Lyme disease. (Related: "Andean Pumas Bring National Park in Argentina Back to Life.")

But puma populations are feeling the squeeze from the San Francisco Bay Area down to southern California. In the East Bay, primo puma habitats are surrounded by eight-lane freeways on one side and the vast, central California agricultural sprawl on the other.

Without new cats coming in to mix up the gene pool, isolated populations can fall prey to inbreeding and a buildup of harmful genetic mutations. Isolation is already a problem for southern California's pumas, and especially for Florida's highly inbred panther population. Now, scientists are studying whether northern California's pumas are headed in the same direction.

"We know that these cats are squeezed. And one of the things that we'd like to learn is, what is the risk of these populations becoming increasingly isolated, making them no longer viable?" McDonald says.

And that's not all that's threatening these cats: There are rodenticides, errant motorists, and livestock owners wielding permits that allow them to kill pumas considered a threat.

"People's attitudes about lions run the gamut," says Marc Kenyon, senior environmental scientist with the California Department of Fish and Wildlife, who has studied mountain lions for more than a decade. "What it really comes down to is talking with people, helping them understand what pressures you're facing, what pressures lions are facing."

Puma Projects

The Bay Area Puma Project has been working in the East Bay for just a few years. They're using a network of trail cams and tracking collars to study how local lions use the landscape—data that could help inform decisions about conserving land that mountain lions will actually use. Farther south, the Santa Cruz Puma Project is doing similar work with pumas living in the Santa Cruz Mountains. The project employs high-tech tracking collars that give researchers information about not only where the cats are, but also what they're doing.

Scientists are trying to map out how pumas in these populations are related to one another, and whether they're at risk for harmful inbreeding effects. To do this, researchers collect biological samples in the field and send them to the Veterinary Genetics Laboratory at the University of California, Davis for genetic sequencing.

So far, the Bay Area Puma Project has collected about a dozen of these samples. Recently, they slipped tracking collars on two cats in eastern San Jose. Both females, one of the pumas now has a young kitten. The tracking data suggest both lions are doing what lions tend to do: avoiding people. "They're very close to the neighborhoods, but they never go in," McDonald says.

Studying cats that live near cities is only one part of the equation, though. Scientists also want to compare the behavior and genetics of urban pumas with those that haven't grown up near a constant human presence.

"We're dealing with a highly adaptable species that essentially can make a living almost anywhere," Kenyon says. "The lions who live now in Santa Monica or Santa Ana or the Bay Area—they live around people all the time. That is their habitat. It's not like you're taking a country bumpkin lion and plopping him in the middle of the big city."

Ghost Cats

Studying mountain lions is not easy, as it's tricky to coax the cats into appearing. Often, researchers—including Pickens and Hanley—attempt to do this by setting out road-killed deer carcasses. Covered with flies and smelling like a decaying deer ought to, the baits are supposedly irresistible to hungry pumas.

Today, though, has been a bit unlucky.

Beneath a sky filled with golden eagles and the sleek white domes of the Lick Observatory, the signs of pumas are everywhere. There are tracks in the dust, scratches on a tree, a punctured deer skull, tufts of fur in the leaves. But no pumas.

"You're not going to see them unless they want you to see them," Pickens says. "They melt into this landscape like nothing."

With the evening temperature plummeting, and no cats ready for trapping and fitting with a tracking collar, Pickens and Hanley pack up for the night.

Pickens will retreat to the quiet isolation of a research station in the hills, and Hanley gets ready to brave a jammed freeway heading north.

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