A small population of mountain lions hemmed in by a network of busy Los Angeles freeways could go extinct in a matter of decades if new blood isn't added to the gene pool and reproduction rates aren't maintained, researchers warn.
The improbability of the big cats crossing traffic-heavy freeways to get to the Santa Monica Mountains National Recreation Area has earned them a measure of celebrity as each new litter of kittens is photographed and documented.
But it is that isolation, combined with the mortal dangers of passing vehicles and the introduction of rodenticides in the food chain, that could lead to their demise, researchers warned in a new report released Tuesday.
"Fifty-plus years ago when the 101 Freeway was built, no one was thinking about wildlife connectivity," said Seth Riley, a National Park Service ecologist and associate adjunct professor at UCLA who was a senior author of the study. "We have worked for years with our partners to increase connectivity across the 101 for all animals, but this study really drives home how serious the threat is for mountain lions, the species most at risk of being lost."
The National Park Service has monitored more than 30 mountain lions in and around the Santa Monica Mountains since 2002. But in the coming decades, the genetic diversity of the population is expected to decline significantly, affecting the ability of the mountain lions to reproduce, a phenomenon called "inbreeding depression."
Should that occur, the model developed by the scientists predicts a 99.7% chance of extinction within 50 years.
There is hope, however. Researchers determined that the arrival of even one new mountain lion to the range every two to four years should maintain current levels of genetic diversity.
Efforts to make the perilous journey more safe include a possible wildlife crossing spanning the 101 Freeway, which is the biggest barrier between the Santa Monica Mountains and large natural areas to the north. A private fundraising effort to help pay for the project, which is being drafted by the California Department of Transportation, has already been launched.
Only one male mountain lion, dubbed P-12, has been documented successfully crossing the 101 Freeway in 2009.
The findings were published in the research journal Proceedings of the Royal Society B.