Successful California wildlife tunnel just the start for these struggling pumas

It’s a mystery how 157M, the legendary mountain lion that wandered into San Francisco in January, charted his safe path across interstate traffic. 

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Roads pose major danger to pumas like 157M that hail from the Santa Cruz Mountains, one of the groups that state officials recently listed as threatened under the California Endangered Species Act. Cars kill them or they stay isolated, leading to increased inbreeding.

But the latest data from a wildlife tunnel on Laurel Curve, a white-knuckle bend on Highway 17 in the Santa Cruz Mountains, offers some tentative hope for this type of conservation tool. At least four lions have padded through the undercrossing since it opened in late 2022, and with the addition of new fencing, none have died there. 

“It is certainly a success story, and it shows that these crossing structures can be successfully used by mountain lions, but it’s not the whole picture,” John Morgan, a UC Santa Cruz Ph.D. candidate who works in the region’s leading mountain lion lab, told SFGATE. “We need more of these types of crossing structures, whether it’s on other parts of Highway 17 or on some of the larger highways that would allow for connectivity to other parts of the state. That’s really what’s going to be important for restoring genetic diversity.”

The Santa Cruz Puma Project — a collaboration between UC Santa Cruz and the California Department of Fish and Wildlife — reports that cars have killed at least 33 mountain lions in the Santa Cruz Mountains since 2016. By tracking their movements with radio collars, the project  that they often tried to cross Highway 17, which bisects the mountains, at Laurel Curve. 

The research organization Pathways for Wildlife also discovered that Laurel Curve stood out as a hot spot for roadkill of all kinds. The group reported that the curve was responsible for 34 out of the 77 animals (mostly deer) hit on Highway 17 in Santa Cruz County between 2013 and 2016. Guided by this data, Caltrans, the Land Trust of Santa Cruz County — which protected about 800 acres around the site — and a local tax measure contributed at least to the Laurel Curve project.

Pathways for Wildlife has now released findings from roadkill surveys and cameras footage from  and 2024, the first two years of the open passage. Roughly 1,000 animals per year are using the crossing, according to the Land Trust, including black-tailed deer, bobcats, gray foxes and skunks (the organization shared a highlight reel on YouTube). The only recorded roadkill was a mountain lion in 2023, prompting Caltrans to extend the directional walls that guide animals to the tunnel. Pathways plans to release its next batch of data by the end of 2026. 

“It’s been really interesting that a lot of female deer with fawns have been traveling, and that’s huge because now we know genetic flow is happening,” Tanya Diamond of Pathways for Wildlife told SFGATE. “And there are also deer, bobcat and gray fox that are commuters now, where the crossing is part of their daily or weekly movements.”

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Diamond is holding out that the area’s dwindling mountain lion population might still discover the crossing for regular use, too. “We’ve talked to other folks who build crossings in other countries and states, and we’re not the only ones not getting a ton of lions at first,” she said. “So I feel really good that we actually got a couple lion detections during the first year. And I’m grateful that we have more time, because we could get a lion that all of sudden decides the crossing is part of their home range.”

Morgan has his sights set on the suite of additional wildlife crossings planned for the region, which will hopefully not only reduce mortalities from cars but also help Santa Cruz area mountain lions to branch out and breed with other populations. There’s one in the works on a different section of Highway 17, a second in Coyote Valley and a third over Highway 101 in San Benito County. 

“Those larger highways, such as the 101, pose an even greater barrier and mortality risk,” Morgan said. “So it’s really with those larger highways where we’re seeing genetic isolation.”

Meanwhile, 157M, called “majestic” by the Pacific Heights resident who found him on the steps of her apartment, now has a collar tracked by the Santa Cruz Puma Project. His last location shows him roaming open space near the Los Altos Hills.