We’re the Biggest Threat to California’s Mountain Lions, But We Can Also Help

Even though mountain lions in southern California are safe from being hunted, a new study has found humans are still their leading cause of death putting their future survival in question.

For the study, which was just published in the journal PLOS ONE, researchers from the University of California, Davis, tracked radio-collared mountain lions and used genetic analysis over a period of 13-years to see how many were surviving, what was causing their deaths and how their future looks with a growing population of more than 20 million people.

They found that humans caused more than half of the known deaths of the mountain lions studied. While they’re considered a protected species who aren’t hunted, they still suffer from illegal shootings, human-caused wildfires, removals to address public safety and being legally killed for preying on domestic animals.

They also found the most common cause of death is being hit by cars. According to the researchers, the threat of being hit by cars is being made worse by I-15, an interstate highway that connects San Bernardino, Riverside and San Diego counties, which has become virtually impossible for these big cats to cross.

Their inability to move freely has isolated populations in the Santa Ana Mountains and raised concerns about the added threat of losing genetic diversity.

“Nowhere in the U.S., outside of the endangered Florida panther, have mountain lion populations been documented that are this cut off and with survival rates this low,” said lead author Winston Vickers, an associate veterinarian with the UC Davis Wildlife Health Center at the university’s School of Veterinary Medicine.

“This means that the odds of an individual animal making it across I-15, surviving to set up a territory, successfully breeding, and then their offspring breeding so the genes are spread throughout the population is harder to have happen naturally than one would expect.”

During the study, only one male successfully made it across and later had four cubs before he was killed. Unfortunately, one was poisoned, one was hit by a car, and another was taken into captivity for becoming acclimated to people.

The lone female survivor in the wild did have cubs, one of which is still alive, and now hope hinges on her having cubs of her own. Still, even if she does researchers note they will all have to survive and it will be quite a while before her cubs are grown and have more of their own.

“This population has one foot on the banana peel and one foot on the edge,” Vickers said of Santa Ana’s population. “Whatever we can do, we should do. Other populations are going the same direction, they’re just not as far down the road.”

According to a statement, the outlook is so bad that intervention in the form of moving them might be necessary, but researchers hope that we can turn to other measures that would allow for a more natural recovery, like creating highway crossings.

Conservationists are working to get a crossing for mountain lions built in Santa Monica, who have been isolated by the Ventura (101) Freeway. They hope this won’t just help mountain lions from disappearing like the eastern cougar,  but also a number of other species who could use the bridge, in addition to reducing the risk of car accidents for drivers.

For more info on how to support the project, check out the National Wildlife Federation.

Photo credit: Thinkstock


Mark Donner
Mark Donner2 years ago

If you can spend billions on trashy environmentally unfriendly projects you can shell out a couple of million on highway crossings for wildlife, you California government scumbags.

Siyus Copetallus
Siyus Copetallus3 years ago

Thank you for sharing!

Jennifer H.
Jennifer H3 years ago

Yet another species that we have ruined the habitat for. It will be a hard fight to try to bring them back.

Sarah Lee Watterson

Tragic! Utterly tragic. What is wrong with people??
Even if I was starving to death I could not kill a beautiful animal. And people do it for fun?????for bogus 'control of animal populations '????

claudia S.
Claudia S3 years ago

Thank you

Fi T.
Past Member 3 years ago

Help as we can

Aasim Ahmed
Aasim Ahmed3 years ago

problem is we're often going into their space we have to respect these beautiful big cats give them plenty of space

Aasim Ahmed
Aasim Ahmed3 years ago

mountain lions wolves coyotes should be left alone the problem comes is when we're in they're territory just like Sharks in the oceans & seas are their homes natural sites in US & Canada all over the world need to be protected as these beautiful animals have their homes & families too

Danuta Watola
Danuta W3 years ago

Thanks for sharing

Muriel Servaege
Muriel Servaege3 years ago

Thank you.