The National Park Service says researchers have documented a rare case of a cougar from the Santa Monica Mountains successfully crossing U.S. Highway 101 to live in a range less hemmed in by Southern California sprawl.

The service said Monday it's only the fourth known crossing of the major freeway in 15 years of study.

The subadult male dubbed P-55 crossed the 101 early on July 30 about 45 miles (72 kilometers) west of downtown Los Angeles and is roaming the Santa Susana Mountains.

Male mountain lions need vast territories but the fragmented wilderness of the Santa Monica Mountains and the massive barrier of the 101 is a significant hindrance to dispersal.

The freeway and other roads are life-threatening to the cats -- 17 documented road kills since 2002.