This young mountain lion wasn't so lucky the second time he tried to cross the ten-lane 405 Freeway in the Santa Monica Mountains/NPS file

P-61, a four-year-old mountain lion that safely crossed a 10-lane highway in Santa Monica Mountains National Recreation Area back in July, wasn't so lucky when he tried to cross the same highway earlier this month.

The male cat was killed in the predawn hours of September 7 while trying to cross the 405 Freeway in the Sepulveda Pass area. That was the same area P-61 safetly crossed back on July 19. National Park Service staff say his final GPS point indicates that he was between Bel Air Crest Road and the Sepulveda Boulevard underpass. 

“We’re not sure why P-61 decided to try and cross the 405 Freeway again,” said NPS biologist Jeff Sikich. “Based on his GPS points, he had been staying close to the eastern edge of the 405 more recently. Over the last few years, we and others have gotten remote camera photos of an uncollared male mountain lion that apparently lives in that area. A scuffle between the two could have caused P-61 to move back west.”

P-61's July highway crossing marked the first time during the course of the NPS’ 17-year study of mountain lions in and around the Santa Monica Mountains that a GPS-collared lion had successfully crossed this freeway. Young male P-18 was hit by a car in 2011 also in the Sepulveda Pass area, as was another uncollared male lion in 2009.

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.

Freeways in the Santa Monica Mountains 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, notes the Park Service. 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.

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