Key Takeaways:
California’s iconic Santa Cruz Mountains are an outdoor recreation wonderland. With a world-class network of hiking, mountain biking, and equestrian trails, they draw millions of visitors each year from neighboring Santa Cruz, Santa Clara, San Francisco and San Mateo Counties.
But these same mountains are also an important habitat for one of North America’s largest terrestrial predators: the mountain lion. A new paper in the journal Current Biology looked at how nature visitors and mountain lions safely coexist on these lands.
Researchers wanted to understand how local mountain lions, also called pumas, deal with chronic high levels of recreation in their habitats. In particular, scientists were interested in how the behaviors of both mountain lions and people might contribute to incidences of “conflict,” defined broadly to include both benign events—like reported puma sightings—and instances where mountain lions posed a perceived or actual threat to people or domestic animals.
“These questions are especially important because this is all taking place in a population that’s newly listed as threatened under the California Endangered Species Act,” explained John Morgan, a doctoral candidate in Environmental Studies at UC Santa Cruz and lead author of the study. “Mountain lions in the Santa Cruz Mountains are at increased risk of extinction, due to a lack of genetic diversity and habitat connectivity. So how can we continue to provide recreation opportunities while also protecting habitat in a way that’s safe for people and mountain lions?”
To gain new insights, researchers analyzed six years’ worth of data from 36 wild pumas in the region that had been fitted with GPS tracking collars. The team began fitting pumas with collars in 2020 at a variety of locales in the Santa Cruz Mountains, including Rancho San Antonio and Monte Bello open space preserves, both of which are managed by the Midpeninsula Regional Open Space District (Midpen), a public land management agency in the Santa Cruz Mountains.
Researchers compared the movements of the pumas to those of humans by looking at data from Strava, a fitness tracking app that’s popular among hikers, runners, and mountain bikers.
The overall movements of pumas in the Santa Cruz Mountains showed that they were clearly tuned in to long-term recreation use trends. Pumas were generally proactive in avoiding heavily trafficked trails, particularly areas within 30 meters (roughly 100 feet) of trail sections with the highest average hourly usage. That’s good news for outdoor enthusiasts.
“If you’re a hiker or mountain biker in these spaces, mountain lions already know you’re there, and they’re avoiding the area,” explained Chris Wilmers, a UC Santa Cruz Environmental Studies Professor and senior author of the study. “They know which trails are used, when, and how much, and they avoid places that are consistently busy, rather than just reactively getting out of there when someone comes down the trail. They are taking proactive steps to avoid people.”
These findings fit well with almost two decades of prior research from Wilmers’ lab, The Santa Cruz Puma Project, which has consistently shown that pumas in the Santa Cruz Mountains fear people and often go to great lengths to avoid them.
Within the local mountain lion population, the current study also found some variability in avoidance responses among individual pumas. Some pumas with the most exposure to recreation in their home ranges reduced their avoidance of people and became comfortable using habitats a bit closer to trails. This suggests that some pumas may be somewhat “habituated,” meaning they become less fearful of people after many experiences of hearing, seeing, or smelling people and not being harmed.
To understand the implications of these findings, the team first mapped the locations of 678 human-puma conflict events reported in the Santa Cruz Mountains between 2018 and 2023. These included incidents such as puma sightings, attacks on pets or livestock, aggressive or unusual behavior, or rare attacks on humans. Researchers then used simulations to show how likely mountain lions with different levels of human tolerance would be to use any of the particular areas where those events occurred, versus how likely humans were to use the areas.
The results showed that the conflict locations were generally avoided by all pumas, regardless of their level of human tolerance. Any potential effects of habituation on which habitats the cats chose to use did not seem to explain the locations of human-puma conflict in the Santa Cruz Mountains. Instead the locations were better explained by recreational intensity.
These findings suggest that more human-tolerant pumas are not more likely to be responsible for conflict, at least when it comes to their habitat selection. In fact, their behavior may help them share landscapes with people, by minimizing the amount of habitat pumas would otherwise lose to people in these human-dominated landscapes.
The paper’s insights could help inform new approaches to wildlife management.
“The long assumption here in the U.S. and beyond has been that habituation equals dangerous, with the result that wildlife agencies generally kill any carnivore they think is becoming habituated.” explained Mark Elbroch, director of the puma program at conservation organization Panthera and a coauthor of the study. “This research suggests that habituation shouldn’t be viewed as black and white, at least, and there may be a spectrum of habituation that is in fact supporting peaceful coexistence between people and these amazing animals.”
Researchers say people also have a part to play in reducing conflict with pumas. The study shows that human behavior is actually a more important factor in minimizing overlapping space use than the behavior of individual mountain lions. That finding may hold important lessons for land managers. Trail access policies that maintain consistent and predictable patterns of human presence — like nighttime trail closures and limits on backcountry access — could help pumas successfully avoid people.
The Midpeninsula Regional Open Space District, which funded and contributed to the study’s research, manages a connected greenbelt of more than 70,000 acres of public open space in the Santa Cruz Mountains. Midpen sees an estimated 2.5 million visitors a year to their 25 publicly accessible open space preserves, according to a 2023 estimate. Funding regional studies like this provides an opportunity for local scientific insights in the design of their programs and management.
“We are excited to be a part of this much-needed study that researches how preserve users and mountain lions share space in the Santa Cruz Mountains,” said Matthew Sharp Chaney, a wildlife biologist with Midpen and a coauthor on the study. “We are lucky in this region for our community to have access to biodiverse landscapes, and studies like this help us make science-based land management decisions that will preserve and protect the wildlife and people that love these open spaces for decades to come.”
The mountain lions that rely on open space lands in the Santa Cruz Mountains are, in turn, crucial for supporting and sustaining ecosystem function. Pumas feed on deer, create scavenging opportunities for other wildlife, generate carcasses that add nutrients to the soil, and might even reduce the prevalence of lyme disease by altering the movement patterns of other wildlife species in ways that expose them to fewer ticks. Understanding the factors that influence human-mountain lion interactions gives land managers and state agencies a greater ability to, both proactively and reactively, respond in the interest of both public safety and protection of the iconic, keystone species that is the mountain lion.
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© Sebastian Kennerknecht
