Mountain Lion Crosses 405 Freeway

This photo of P-61 was taken just a couple of weeks before he crossed the 405, becoming the first collared cat to do so in the almost 20-year National Park Service study. As we know, these freeways, more often than not, act as deadly barriers for these animals, which makes building wildlife crossings so critical. Photo by Jason Klassi

The National Park Service has documented a rare case of a mountain lion crossing the 405 Freeway in the Sepulveda Pass area. The male mountain lion known as P-61 made his way east of the massive freeway sometime between the hours of 2 and 4 a.m. on the morning of July 19. 

This is the first time during the course of the 17-year study of mountain lions in and around the Santa Monica Mountains that a GPS-collared lion has successfully crossed the 405 Freeway. In the same general vicinity where P-61 likely crossed, P-18 was hit and killed by a vehicle in 2011 and an uncollared lion was hit and killed in 2009. 

“Although P-61 successfully crossed the 405, his feat is a reminder of how challenging Southern California’s road network is for mountain lions and other wildlife, as well,” said Jeff Sikich, biologist for Santa Monica Mountains National Recreation Area. “Others haven’t been so lucky.” 

When the 101 and 405 freeways were built they created an impassable barrier for the mountain lion population of the Santa Monica mountains, trapping them on an island of habitat in the coastal range. This has caused dangerously low genetic diversity levels. Young lions cannot disperse out of the range into new areas and animals with different genetics cannot cross into the range. It’s a recipe for local extinction. During the course of the study, researchers have documented numerous mountain lions traveling right up to the edge of the freeway and not crossing. Other cats have tried to cross and died. It is vanishingly rare for a mountain lion to successfully cross a multi-lane freeway without injury.

The most well-known example of a mountain lion crossing the 405 Freeway is P-22, the only known mountain lion in Griffith Park, and the poster-cat for urban wildlife awareness. P-22 was only collared after he arrived in Griffith Park and little is known about his journey. However, DNA testing indicates that he was born in the Santa Monica Mountains and somehow made his way across the 405 and 101 freeways, and through some of the most densely developed urban landscape in LA, before reaching the safety of Griffith Park, where he has lived for more than seven years. 

There may be another mountain lion in the relatively small area between the 405 and 101 Freeways. For the past five years, surveillance camera footage has occasionally captured images of an uncollared male lion in the area P-61 has now entered.

Mountain lions can be territorial, and males have been known to fight each other to the death for control of a range if there are not adequate resources to support more than one cat, or enough room for the adult cats to avoid one another.  That is one of the reasons young animals need room to disperse.

“It will be interesting to see if P-61 stays in the area, whether he decides to challenge the uncollared lion, or if he heads back to the other side of the freeway,” said Sikich. “Although it’s a relatively small area of habitat, it’s certainly larger than the Griffith Park area and does have a patchwork of natural areas.” 

“Now that P-61’s GPS collar is recording data points in the area, it’s a good opportunity for researchers to learn about landscape connectivity in the highly fragmented area.” she added.

P-61 was first captured and outfitted with a GPS collar in October 2017. He weighed 119 pounds at his most recent capture and is believed to be approximately four years old. 

Since 2002, the National Park Service has been studying mountain lions in and around the Santa Monica Mountains to determine how they survive in an increasingly fragmented and urbanized environment.The groundbreaking project has gathered data on movement patterns, behavior, and genetics and identified the species greatest vulnerabilities—rodenticide poisoning, habitat loss, lack of genetic diversity and roadstrikes on freeways like the 405.

The California Department of Fish and Wildlife is responsible for overseeing the management and conservation of mountain lions in the state.n 

Santa Monica Mountains National Recreation Area (SMMNRA) is the largest urban national park in the country, encompassing more than 150,000 acres of mountains and coastline in Ventura and Los Angeles counties. A unit of the National Park Service, it comprises a seamless network of local, state, and federal parks interwoven with private lands and communities. As one of only five Mediterranean ecosystems in the world, SMMNRA preserves the rich biological diversity of more than 450 animal species and 26 distinct plant communities.


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Suzanne Guldimann

Suzanne Guldimann is an author, artist, and musician who lives in Malibu and loves the Santa Monica Mountains. She has worked as a journalist reporting on local news and issues for more than a decade, and is the author of nine books of music for the harp. Suzanne's newest book, "Life in Malibu", explores local history and nature. She can be reached at

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