Mountain lion P-61, shown here when he was captured in October 2017 in the eastern end of the Santa Monica Mountains, crossed the 405 Freeway last month. (photo courtesy of the National Park Service)

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 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 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.

Freeways in the area act as fences for the local mountain lion population, hemming them in on an island of habitat, which has led to seriously low genetic diversity levels in the Santa Monica Mountains. During the course of the study, researchers have documented numerous mountain lions traveling right up to the edge of the freeway and not crossing.

The most well-known example of a mountain lion crossing the 405 Freeway is P-22, but he was not collared at the time, so little is known about his journey. DNA testing indicates that he was born in the Santa Monica Mountains and therefore had to make his way across both the 405 and the 101 Freeways on his journey to Griffith Park, where he has lived for more than seven years.

In addition to P-61, researchers are also aware of an uncollared male mountain that seems to inhabit the same relatively small area between the 405 and 101 Freeways. Surveillance camera footage occasionally surfaces with images of that lion, assuming it is the same one, dating back approximately five years. For information, visit nps.gov/samo.