New research provides foundation to look at protecting mountain lions, particularly when it comes to Highway 17
An adult male mountain lion called simply “Number 16” by the Santa Cruz Puma Project led a scientifically interesting life for the more than two-year period he was tracked by the UC Santa Cruz-based research project.
According to Chris Wilmers, associate professor of environmental studies at UCSC and head of the Puma Project, the group initially caught and collared Number 16 in Loch Lomond. He then proceeded to cross Highway 17 several times, where he was eventually was hit, but survived. In an unusual move for an adult male, Number 16 then shifted his home range to the Forest of Nisene Marks State Park. Recently, the lion’s tracking collar went on “mortality mode.” The day before Wilmers spoke to Good Times, the researchers found his skeleton.
“He was depredated for killing goats,” explains Wilmers. “There’s a great diversity of opinion on these animals. Some people see a mountain lion on their property and it’s the most exciting thing they’ve ever seen. Other people are scared. Others may see one kill a goat or pet and some choose to let it go and some choose to get a depredation permit from Fish and Game and kill the lion.” Out of the 11 lions that died during the Puma Project’s study, eight were killed after attacking domestic livestock.
The Santa Cruz Puma Project began in 2008, in partnership with the Department of Fish and Game, to better understand mountain lion (or “puma”) behavior, particularly how it is impacted by habitat fragmentation and human development.
“There has really never been much work at all on these large predators in highly developed areas like the Santa Cruz Mountains,” says Wilmers. “Usually, when people have studied a large predator it’s in huge, wide-open protected areas, like Yellowstone. We started this project to look at predators in a more human-dominated landscape.”
The project’s first batch of findings was published in the peer-reviewed science journal PLOS ONE on Wednesday, April 17. The researchers found that mountain lions have two scales they utilize for existing in a human-impacted area: a very remote scale in which they need privacy from humans (meaning they give neighborhoods, roads, and other signs of humans a wide berth) in order to den and reproduce, and a second, more lenient scale in which pumas will traverse these developments in order to travel and find prey.
“We see mountain lions in our backyards and crossing roads and things like that so we think these are places that are a good habitat for them,” Wilmers says. “It turns out that when they are breeding and reproducing they need habitat that is much more remote.”
These findings have implications for applied conservation in the Santa Cruz Mountains, where Wilmers says, “we’ve been very effective at preserving open space.”
“So, knock on wood, mountain lions still have quite a lot of open space to call home,” he says. “The graver threats on the horizon are whether they will be able to get to those open spaces because of roads and development that separates them from those areas. If the animals get isolated into these islands of habitat, we know from experience in other places that they will lose genetic diversity and eventually go extinct.”
He cites creating linkages across highways 17, 101 and 152 as critical next steps for protecting the local mountain lion population.
Five mountain lions have been hit on Highway 17 over the last three years, says wildlife biologist Tanya Diamond, three of which were being tracked by Wilmer’s team. She is working on a plan that would enable mountain lions and other wildlife to have an easier and safer time crossing the highway. Working with Wilmer and the Midpeninsula Regional Open Space District, Diamond presented a connectivity design to Caltrans on Monday, April 15 that drew on the Puma Project’s findings to create a proposal for wildlife-friendly improvements to the road.
Her suggestions include clearing out, enlarging and fixing culverts and installing fencing that would guide wildlife to these under-road passageways. While she would prefer for land bridges to be installed over the highway, that idea faces a few setbacks, including cost and landslide potential. She does still plan to advocate for adding an additional, vegetative lane to current overpasses for animals to use.
If Caltrans likes the report, they would eventually fund, implement and oversee the connectivity projects, which will focus on the stretch of highway between the base of Los Gatos and the Bear Creek Road overpass.
In February 2011, Diamond, who lives near the Lexington Reservoir off of Highway 17, saw a hit mountain lion on the road and pulled over to call the game warden. The animal was so badly injured that it was euthanized. She says Wilmers visited the body and determined it to be an adult male who had possibly been pushed from its territory by a younger male.
“It was such a shame,” Diamond says. “There is all this beautiful open space, we just need to create a safe passage for them.”
With the addition of high medians along the highway, Diamond says more bobcats and smaller wildlife are trapped and killed on the road. Wilmer, too, is concerned about the effect these medians will have on wild animals. “Most of our data comes from before the new median barriers,” he says. “We are worried that those are going to make it more difficult for animals to cross.”
In her presentation to Caltrans, Diamond pointed out the road’s safety index, which demonstrates the risk to all species when vehicle crashes are involved. “Our safety index shows this a human safety issue, along with a problem for mountain lions, deer and bobcats,” she says.
Diamond believes the Puma Project’s research will prove instrumental in mountain lion habitat conservation, starting with her Caltrans proposal.
“I think Caltrans will be more likely to support a bigger request because of the work [Wilmer] has done,” Diamond says. “His research has given me a platform to discuss this with Caltrans.”
Follow the Santa Cruz Puma Project at santacruzpumas.org.
Number 16, an adult male mountain lion tracked by the Santa Cruz Puma Project, is seen in this video “scraping,” a communication behavior used by pumas, in Loch Lomond in 2011.