California mountain lions killed on roads at concerning rates, study shows

A new study from the University of California Davis shows California mountain lions are being killed on roads and highways at high rates.  

The data from the study was published this week.

"The primary findings are two-fold. One is that there are about one or two mountain lions per week that are dying on state highways and there's probably more on city and county roads. The other is that there are these big regional clusters throughout California in the Bay Area, Southern California and the Sierra Nevada foothills," said Fraser Shilling, the Director of the Road Ecology Center at UC Davis.

The numbers, showing one to two mountain lions being killed each week on California roadways, are based on data between the years 2015 to 2022. The number has decreased over the years, but researchers believe that could be due to a decline in the mountain lion population.

"If traffic is not changing and roadkill goes down, that's because there's fewer animals," said Shilling.

The data shows mountain lions are being killed faster than they can reproduce.

"In certain regions, they're under threat of a local extinction. That's a really big deal because if you lose the top predators in an ecosystem, the ecosystem starts to fall apart," said Shilling.

A statewide mountain lion population estimate should be released this year. The last study was conducted in 1996, according to Shilling.

"When we look at a species like this, we can't just rely on 20-year assessment periods. We have to do assessments more often. We have to know what the trends are in these populations," said Shilling.

The study also found some of the most dangerous places for mountain lions to live in Southern California.

"The places they're getting hit a lot are I-15, south of Temecula, the 210 near Altadena, I-8 in San Diego County, Highway 74 through Ortega Highway [in the Santa Ana Mountains] and then Highway 241 in Orange County," said Shilling.

Shilling believes there are solutions that can help curb the problem like fencing and wildlife crossings. The state is investing money into creating more fencing and crossings too, including a wildlife crossing that is being built over the 101 Freeway, near Agoura Hills.

However, Shilling said there can be some problems with the crossings.

"If you have a population of mountain lions and they're divided by something like a freeway then they're gonna be isolated from each other and then you get problems like we have in the Santa Monica Mountains where there's inbreeding and you get this overall depression of the population because they're all related to each other," said Shilling.

On Saturday at the Greek Theatre, people will honor P-22, the famous mountain lion known for wandering the hills near the Hollywood Sign, with a memorial service. The service is sold out. Experts believe P-22 was hit by a car and suffered traumatic injuries before euthanasia.

Another mountain lion, P-81, was also killed in January after experts believe the animal was likely hit by a vehicle.

"P-22 and his death can be an ambassador and can represent the problem to say we really need to address this, and we really need to fix this," said Shilling.