Researchers recently documented a rare case of a cougar from the Santa Monica Mountains successfully crossing U.S. Highway 101 and moving into a range less hemmed in by Southern California sprawl, the National Park Service said Monday.
The subadult male, dubbed P-55, crossed the 101 early July 30 along the steep Conejo Grade about 45 miles west of downtown Los Angeles. P-55 also crossed State Routes 23 and 118 to reach the Santa Susana Mountains, a park service statement said.
It is only the fourth known successful crossing of the 101 in the 15 years researchers have been studying the big cats in the Santa Monica Mountains, a population dealing with inbreeding and a lack of genetic diversity because the mountain range is hemmed in by Los Angeles, its western suburbs and the Pacific Ocean.
Male mountain lions need vast individual territories. But the fragmented wilderness of the Santa Monica Mountains and the massive barrier of the 101 — three or more lanes in each direction — is a significant hindrance to dispersal.
The freeway and other roads are life-threatening to the region's lions: There have been 17 documented deaths on roadways since 2002.
“The overwhelming pattern we've observed through GPS tracking is lions coming up to the edge of a freeway and turning around,” said Seth Riley, a wildlife ecologist at Santa Monica Mountains National Recreation Area, which sprawls over 150,000 acres of mountains and coastline.
Male mountain lions usually leave their mothers at about age 1 to find their own territories. While a male can live with many females in its territory, it will face potentially fatal battles with other males if it can't disperse.
So far in the study, it's rare for a male mountain lion in the Santa Monicas to survive past age 2, according to the park service.
P-55 had recently been fitted with a tracking collar and was seen on video in the backyard of a Newbury Park home the same weekend he crossed the 101.
One proposal to help mountain lions more easily move between the Santa Monica range and the less-confined natural areas to the north would involve building a bridge for wildlife to cross the 101 at Liberty Canyon, which has open space on each side of the highway and is under permanent protection.