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Cars are a major threat to LA's mountain lions; special overpasses could help

The mountain lion known as P-23 crossing a road in the Santa Monica Mountains
The mountain lion known as P-23 crossing a road in the Santa Monica Mountains
The National Park Service

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This week The National Park Service found the body of the mountain lion known as P-23 in the Santa Monica Mountain area, near Malibu Canyon Road. It appears she was struck by a car.

NPS has been studying the big cats around the Santa Monica Mountains since 2002, and they say a total of 18 mountain lions have been struck and killed by vehicles over that period. 

Seth Riley is one of the NPS researchers studying the mountain lions, and he said these urban cats face unique challenges. 

"Major freeways like the 405 and the 101 separate the Santa Monica Mountains from everywhere so the roads are a major barrier to movement back and forth."

However, there is a solution: building crossings over roadways for the mountain lions and other animals. The NPS is part of the effort to build one of these overpasses over the 101 freeway near Agoura Hills. 

Riley said the 101 crossing project is moving along and Caltrans is expected to put out its document on the environmental impacts of the project this month. The next steps will be the design phase and then actual construction, so it will be a couple of years before the crossing is actually complete, Riley said. 

"The major challenge is that putting a big, wide, 165-foot, vegetated overpass over that freeway costs a lot of money. So we're looking at $60 million or so."

Making sure the crossings feel like an extension of the animals' natural habitat is key, Riley said, so this crossing will be a wide, vegetated path with sound walls.