By Steve Gorman
LOS ANGELES (Reuters) - Mountain lions have been dying on California highways at the rate of at least one or two every week in recent years, a roadkill toll that may exceed healthy reproductive levels for the big cats, new wildlife mortality data showed on Thursday.
Maps documenting deadly highway crossings - clustered most heavily in Southern California, the San Francisco Bay Area and the western Sierra Nevada foothills - were released by the Road Ecology Center at the University of California (UC) at Davis.
The data adds to research showing mountain lions, also known as cougars or pumas, are under growing pressure from traffic and urban sprawl that have left their territories increasingly isolated from one another, shrinking their gene pools.
"Over time, extra mortality from cars, especially for small, isolated populations, adds significantly to the threats they already face, Fraser Shilling the Road Ecology Center director, said in releasing the latest maps.
A well-known case in point was the Los Angeles-area mountain lion dubbed P-22, a radio-collared puma that became a wildlife celebrity after managing to cross two busy freeways to take up residence in the Hollywood Hills around Griffith Park.
P-22's demise came after the cat, a male believed to be 12 years old, was struck by a car and injured. Wildlife officials captured the lion in December and euthanized him after a medical exam found P-22 badly weakened from various ailments.
"The tenacity of P-22 in life and the final tragedy of his death from a vehicle collision highlights the plight of mountain lions throughout California, constantly under threat from traffic while living their natural lives," Shilling said.
Another radio-tagged puma, P-81, was found dead from a possible vehicle strike last month in the western Santa Monica Mountains.
The study cataloged a total of 535 mountain lion deaths on some 15,000 miles (24,140 km)of state-managed highways over eight years, from 2015 through 2022. That tally amounts to nearly 70 a year, but researchers said the true toll would likely be higher if city and county roads were counted.
The mortality rate also was found to have declined by about 10% over the past seven years. But the trend suggests cougar populations gradually declining as the pace of highway deaths matches reproductive rates, researchers said.
Publicity surrounding P-22, famously photographed prowling past the landmark Hollywood sign, helped raise funds for the world's largest wildlife overpass, over U.S. Highway 101 near Los Angeles. The project broke ground last April. A public celebration of P-22 is planned for Saturday in Griffith Park.
(Reporting by Steve Gorman in Los Angeles; Editing by Sandra Maler)