Mountain Lions: Real Threat to Bay Area Hikers?

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An empty trail can be daunting. A Bay Curious listener asks should he be scared of mountain lions? (Christian Arballo Images via Creative Commons)

You know when you go out hiking and before you’ve even started, you see a sign like this?

If you encounter a mountain lion, face lion, back away slowly. Be large. Shout. Keep children close. Pick up children without bending. If attacked, fight back.

If you're the nervous type, it can be unsettling.

A warning sign is posted at the Los Trancos Open Space Preserve in San Mateo County. It's part of the Midpeninsula Regional Open Space Preserve. (Creative Commons via Flickr)

Bay Curious listener Dave Fairburn wanted to know how much stock to put in these warnings -- he's a frequent hiker. He also wanted to know more about the Puma concolor, an animal that also goes by cougar, panther, ghost cat, mountain lion and more.

“I’ve never seen a mountain lion,” Fairburn says. “I don’t know anything about them, so I was kind of curious. Is it legitimate? Are they really here? Do I really need to think about them?”

Mountain lions are a top-of-the-food-chain type predator. Females can weigh between 80 to 85 pounds, and males get as big as 150 pounds.


Dave and I met at UC Santa Cruz to get answers from Associate Professor of Environmental Studies Chris Wilmers. He runs the Santa Cruz Puma Project, where researchers have been studying mountain lions for almost a decade. Together we walk off campus to an area with lots of redwoods trees, where mountain lions roam.

UC Santa Cruz Associate Professor of Environmental Studies Chris Wilmers (left) and Berkeley resident Dave Fairburn in the redwoods near campus. (Vinnee Tong/KQED)

One of Fairburn’s first questions: How many mountain lions are there in the Bay Area?

“The short answer is, I don’t really know,” Wilmers says. His best guess is there are probably 50 or 60 mountain lions in the Santa Cruz Mountains, which stretches from south of San Francisco to Watsonville.

“And that’s probably the largest chunk of contiguous habitat for mountain lions in the Bay Area, so that would be the largest sub-population,” Wilmers says.

California’s Department of Fish and Wildlife estimates that there could be 4,000 to 6,000 mountain lions in California.

How worried should we be?

Our question-asker Fairburn worries when he’s out hiking and wants to know: Is he safe?

Wilmers says it’s important to keep things in perspective. Mountain lions actually go out of their way to avoid us. One way mountain lions avoid us is by shifting to a more nocturnal schedule than typical when they're in areas where humans go.

And as far as tracking us as prey? No, not a thing.

“What they really love to eat is deer,” Wilmers says. “About 95 percent of the calories they ingest come from deer. Their behavior is to try to avoid you, rather than seek you out as prey.”

The Department of Fish and Wildlife keeps track of mountain lion attacks on humans. In the past three decades, there have been three deaths statewide, as well as 12 attacks that were not fatal. And no attacks on humans at all since 2014.

Wilmers likes to tell people it’s far more risky to drive a car or even brush your teeth. One of his favorite comparisons is how many people impale themselves on their toothbrush and die.

“You know, it’s something like 10 or 11 a year,” Wilmers says. “So probababilistically, you’ve got a greater chance of impaling yourself on your toothbrush than being killed by a mountain lion, but we don’t think of the toothbrush as being dangerous.”

If they’re avoiding us, this made Fairburn wonder about the one or two animals a year that find their way into towns, often on the peninsula. Wilmer says they’re basically lost.

“Those are almost always young animals, usually young males that are out looking for a new territory,” Wilmers says. “They essentially make a mistake and wander into a downtown.”

So, while humans are relatively safe, it's probably less safe for Fido and Fluffy. And for livestock in more remote areas.

Mountain lions are tawny in color. Females can weigh 80 to 85 pounds and males can be as big as 150 pounds. (Creative Commons via Flickr)

Are They at Risk?

We’ve mostly been talking about whether we’re in danger of mountain lions. But it’s also worth asking: Are they in danger of us?

Mountain lions depend on having space to roam. The more space humans take up, and the more open space we cut into smaller pieces with roads and freeways, the more we put them at risk.

There are efforts to build tunnels under Highways 101 and 280 to give the mountain lions a way to get around. That’s because so many are being hit and killed by cars. Last year, UC Davis counted 48 mountain lions deaths on California roads. But the co-director of UC Davis's Road Ecology Center, Fraser Shilling, says the actual number of roadkill deaths could be double that.

If the population of mountain lions in the Santa Cruz Mountains ends up isolated -- and can’t diversify its gene pool -- Wilmers says they’d probably go extinct within 100 years.

How Do They Mate?

If there are so few and if they’re pretty spread out, how do they find each other in the first place? You know ... to mate?

The males pick a spot on what’s basically a “mountain lion highway” in the woods. They scratch the ground, pee and leave.

When a female comes looking for a mate, if she likes what she smells, she caterwauls. It sounds kind of like your neighborhood cat in heat, but a lot louder and deeper. Wilmers says researchers think mountain lions set up these communication hot spots in places where they can hear the female from long distances.

Once she caterwauls, she waits. And if a male finds her, the happy couple spend two or three days together. Three months later, baby mountain lions!