Well-Known Orange County Mountain Lion F312 Killed in Road Collision

A mountain lion known as F312 was killed by a vehicle while crossing a road in the Santa Ana Mountains on Thursday.

The female mountain lion had been nicknamed "Uno" due to an old eye injury, which also made her easily identifiable for photographers, wildlife officials, and local residents. She was a common sight on trail cameras and home security systems in the hills of Orange County.

"She also was somewhat famous for her seeming laissez faire demeanor around people at times — often paying little attention to hikers or others she might encounter," the California Mountain Lion Project wrote in a Facebook post announcing her death. "On one occasion she walked right past the admission booth at one of the local wilderness parks without even a side glance (she didn’t have to pay)."

F312 was struck and killed on Santiago Canyon Road, which she'd successfully crossed before.

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The mountain lion F312

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Collin Eckert

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UC Davis California Mountain Lion Project

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Despite efforts from local veterinarians, O.C. Animal Care officers, and local residents to save the animal, F312 died before they could begin significant treatment for her injuries.

Tiffany Yap, a senior scientist with the Center for Biological Diversity, said the news was heartbreaking, if not uncommon.

"We've really sliced through and fragmented the habitat for mountain lions, but also for a lot of other animals," Yap said. "And we did it in this way without really knowing or thinking about how they move."

Yap said that without wildlife crossings or other measures to accommodate wildlife in the built environment, mountain lions in the Santa Ana Mountains and other parts of California face threats to their survival beyond the risk of being hit by cars.

"We know these mountain lion populations are struggling, especially where Uno is," Yap said. "She was in the Santa Ana Mountains. They have the lowest genetic diversity on record, aside from the endangered Florida panthers, who almost went extinct because they were having reproductive issues."

In 2022, another well-known local mountain lion, P-22, also died after sustaining injuries from a car accident while crossing a road. In P-22's case, the mountain lion survived the immediate injuries but was euthanized after his condition failed to improve during treatment.

F312 and her kittens.

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Collin Eckert

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UC Davis California Mountain Lion Project

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P-22 helped raise awareness of the unsafe routes across freeways and roads that many mountain lions and other animals traverse due to their dwindling habitats. The world's largest wildlife crossing is now under construction above the 101 in Agoura Hills, near the route that P-22 would have had to cross to reach his former home in and around Griffith Park.

According to the California Mountain Lion Project, car accidents are the most common cause of death for mountain lions in Southern California.