Sixty feet high in the forest canopy, the puma begins to fidget. From the tree next to her, biologist Paul Houghtaling shakes branches and yells to frighten her from her perch. Disgruntled, the puma grudgingly descends the tree’s trunk head first, clinging to the bark and hissing at the researchers waiting below.
“It wasn’t the most graceful thing,” said Houghtaling, the field biologist for the Santa Cruz Puma Project (SCPP), when telling the story. “She was backing out, snarling like a dragon.”
Called 38F, this female puma is one of many caught and collared by SCPP. Partnered with UC Santa Cruz and led by UCSC professor of environmental studies Chris Wilmers, SCPP researchers have spent the past five years collecting data to better understand puma behavior, physiology and ecology, and how each are affected by habitat fragmentation in the Santa Cruz Mountains.
Since 2008, Wilmers and the 10 graduate students and staff members involved with SCPP have caught and tagged 38 pumas from their 17,000 km2 study region in the Santa Cruz Mountains. Today, this landscape is a mosaic of open forest, rural neighborhoods and roads — all of which are surrounded by cities. The researchers collect data from them with GPS collars, samples from deer kill sites and 44 trail cameras.
SCPP published their first study, which encompassed four years of data, on April 17. The results confirmed their prediction that pumas tolerate human activity in their basic subsistence habits — feeding and moving throughout their territories — but they need larger environmental buffers to conduct reproductive behaviors, which include raising kittens, communicating and mating.
“Just because you see mountain lions doesn’t mean it’s good mountain lion habitat,” Wilmers said. “What they really need to sustain their populations are big open spaces that allow them to find mates and reproduce.”
According to the study, healthy reproduction rates in puma populations require access to mates and success at raising kittens. Like humans, puma romance begins with communication — but instead of Match.com, male pumas use scent markings to advertise their presence to females. These occur at scrape sites, where pumas kick up piles of duff and leaves and urinate on them. Often, like in 38F’s territory, multiple male pumas have to duke it out for the strongest scent.
“They’re having a pissing contest with each other, essentially,” Houghtaling said.
When a female puma likes what she smells, she answers with a screeching call, also known as caterwauling. If all goes according to plan, the two will meet up and mate for several days. The female will den and give birth to kittens several months later.
As open space becomes more fragmented, Wilmers said being a responsible wildlife neighbor will become increasingly important to the survival of puma populations.
“The more fragmented a habitat becomes, the smaller the population’s going to be,” he said. “[It becomes] a bigger deal, things like depredation, because you’re killing a smaller and smaller population.”
While pumas are characteristically shy animals that avoid human neighborhoods, the study shows they occasionally eat pets left outside after dark, said Yiwei Wang, a graduate student who is part of the project. At night, when humans go to sleep, the decrease in human activity invites pumas to venture into the rural neighborhoods to look for food.
Wilmers said pumas have the highest chance of being shot in rural neighborhoods, where many people have pets that could potentially be prey for pumas. It is legal in California for landowners to shoot mountain lions that threaten their property — according to the published study, eight of the project’s collared pumas have been shot for preying on domestic livestock since 2008.
Wang and other members of SCPP reach out to landowners in rural communities close to open space to educate them about how to minimize conflict with pumas.
“It kind of comes down to, are we going to be good neighbors?” Houghtaling said.
For SCPP researchers, being a good neighbor means putting pets in sheds at night, when lack of human activity might entice pumas to infiltrate neighborhoods in search for food.
Roads are another cause of puma mortality, particularly Highway 17. Two of the project’s collared pumas have been hit by cars, one of which died from the accident.
“There’s potential for making these large highways more pervious for animal movement,” Wilmers said, “by building overpasses or underpasses for wildlife to cross the highway rather than crossing the road and risk getting hit by a car.”
SCPP has a working relationship with Caltrans, the state agency that oversees planning and construction of highways, bridges and railways. With help from SPCC, Caltrans is currently working to draw up a plan to implement these changes, Wilmers said.
While being shot or hit by a car is unfortunate for individual pumas, Wang said, habitat fragmentation poses the largest threat to the population in the Santa Cruz Mountains, which is currently at a healthy 70–100 adult individuals.
“Getting some individual [pumas] killed doesn’t necessarily impact the survival of the population,” Wang said. “We’re more concerned for conservation purposes of retaining valuable habitat and making sure that development doesn’t occur in places that are really important to pumas right now.”
Among these important areas are forested corridors connecting areas of open space, which serve as routes of access for pumas. Cutting these off affects their ability to find mates and reproduce. It also limits the ability for new individuals to join the population, Houghtaling said, which is vital to the population’s future genetic health.
The Pumas of the Project
“Every individual animal is interesting,” Houghtaling said. “They have their quirks, they’ve had their experiences and their ways of relating to things that are a little bit different from one individual to another.”
Of the original 38 pumas collared, 14 are still alive. One male, 16M, became a local celebrity when stories of his escapades on Highway 17 spread. 16M crossed the highway more than 30 times, survived getting hit by a car and boldly changed the location of his territory, risking being killed by the males whose territories he expanded into. He was a favorite among the researchers, Wang said, until he was shot in November 2012 for preying on livestock.
3M was the first male collared in the Santa Cruz Mountains. According to one of Houghtaling’s SCPP blog updates, 3M taught the researchers lessons about important corridors in neighborhoods, the significance of marking sites and the importance of “patience, ingenuity, perseverance, versatility and humility.”
“3M was like a ghost. His collar was junk, it broke right away and would very rarely send us a data point,” Houghtaling said. “That cat really pushed our edges to think outside the box.”
Houghtaling said 3M’s elusive behavior forced the researchers to become more creative with technology, like using satellite transmitters to monitor when a lion is scavenging a deer and sending updates from GPS devices directly to emails and smartphones.
The researchers have refined their methods since they first captured 3M and now have several ways of catching pumas. They use box traps baited with a fresh kill, padded snare traps or hound dogs to track and “tree” an individual, or chase it up a tree, like with 38F.
“It’s always very awe-inspiring to see such a large, powerful animal and then kind of render it helpless for a little bit,” Wang said.
Out in the field a few weeks ago, a scrape site in Cemex Redwoods caught Houghtaling’s eye. He squatted low to inspect a paw print in the exposed earth, still moist from the puma’s recent presence. This scrape may have been made by the uncollared male in 36M’s territory that had been eluding the researchers.
Houghtaling radioed Dan Tichenor, the houndsman. Tichenor brought out Osage, a wizened Plott hound, to inspect the site. Osage sniffed the scrape and his tail started wagging. He barked in a direction off the trail, but didn’t give the particular howl that signals he found a fresh scent. The uncollared male had evaded the researchers once again.
Tichenor said hounds are effective in chasing pumas because pumas instinctively avoid conflict with other predators they evolved with, such as wolves.
“These hounds may be getting by on the wolves’ coattails, so to speak,” Tichenor said.
Once the hounds have “treed” a puma, the researchers shoot it with a tranquilizer dart. The drugs take several minutes to have an effect. That brief window of time often involves a wild chase to ensure the puma doesn’t pass out in a dangerous situation, such as in water.
“Their safety is our number one priority,” said Veronica Yovovich, a grad student with SPCC. “No data is worth hurting a puma over. If things look risky at all, we will back off rather than ever put a puma at risk.”
When a puma has safely fallen asleep, the researchers check its vital signs, collect various data and samples and put the collar on.
After a puma has been captured and let loose, the researchers monitor its movements with three devices on the collar: a GPS, a magnetometer that serves as a compass and an accelerometer to measure vibrations. Walking, pouncing, running and climbing, among other movements, each have a specific signature in the accelerometer data. The researchers found the key to these signatures by putting captive pumas on treadmills.
“Everyone’s like, you can never get a mountain lion to run on a treadmill,” said Gabriel Elkaim, the project engineer. “Turns out a leg of ham will get the mountain lion to run on a treadmill.”
Collars, Kittens and Deer
Now that one data set has been published, SCPP is looking to broaden the horizons of the original study.
Elkaim and Wilmers have been working on a new collar design that creates its own energy with a Faraday generator — a device that uses energy from friction caused by the animal’s motion — and solar panels. This would allow the collars’ battery life to last for 10 years rather than the current 1–2 years.
Incorporating these generators into the study would save the time and energy taken to re-collar animals on a regular basis, something that would allow for a larger study size.
“It’d be awesome,” Houghtaling said. “Instead of 38 [pumas], we could be at 70.”
Wilmers hopes to collar more kittens to better understand how habitat fragmentation affects their survival. This tricky business involves finding dens and visiting them when the mother isn’t around. Wilmers also hopes to start tagging deer, whose populations are declining in the western United States, he said. This may be due to any number of factors, including being eaten by pumas, but Wilmers said he predicts a future study will point to habitat fragmentation.
Yovovich’s current study — a facet of SCPP’s larger project — focuses on the effect of pumas on subsequent links in the food chain, such as deer and plants.
“Conservation goals are to have a healthy, intact ecosystem,” Yovovich said. “Plants co-evolved with grazers and grazers co-evolved with carnivores, and so the best ecosystem is to have all those pieces in there sort of feeding into each other.”
Along with depredation, predators affect deer with what Yovovich calls an “ecology of fear.” This model suggests prey species avoid places where predators have an advantage, which allows the flora in these “feared” areas to flourish from lack of grazing. For her study, Yovovich predicts that deer will frequent areas higher in human activity because pumas characteristically avoid these areas.
In the eastern United States, pumas and wolves — top predators — went extinct during the 18th and 19th centuries due to human expansion. Today, deer populations have exploded in their absence and forest ecosystems are severely depressed due to extreme overgrazing, said John Laundré, an instructor at Oswego State University of New York.
Laundré said opponents of reintroducing pumas in the highly developed east argue pumas can’t tolerate humans and even pose a threat to humans. Data from SCPP shows the contrary.
“People in the west are beginning to realize that they’ve been living among cougars for quite some time now and they haven’t caused problems,” Laundré said.
Yovovich said aside from having pets eaten, there is nothing to fear from pumas.
“You’re more likely to get killed by your toaster than by a mountain lion,” she said.
Human-puma encounters — in the woods, on roads or in backyards — are inevitable as long as human development cuts into open space and infringes upon pumas’ territories. SPCC aims to educate rural landowners with their findings so these chance meetings can be less harmful for both pumas and humans, Wang said.
“A lot of things about mountain lions are just a matter of conscience,” Houghtaling said. “In the brief encounter that you have with this being — that can be kind of fear-inducing — it’s important to have the context of knowing that it’s having the same experience, asking ‘well, who are you?’”