LOS ANGELES >> A population of mountain lions living in the Santa Monica Mountains faces possible extinction in the near future due to inbreeding, according to a study released Tuesday.
In the study, published in the journal Proceedings of the Royal Society B, wildlife researchers from the National Park Service, UCLA, UC Davis and Utah State University gave the lions a 99.7 percent chance of extinction over the next 50 years unless more lions become part of the gene pool.
Scientists say without any changes, their disappearance would be a rapid descent, with decreasing genetic variability evident as early as 15 years from today, reaching a point of no return in about 35 years.
Efforts to save a group of about 15 mountain lions living in the Santa Monica Mountains are the subject of numerous, ongoing studies pointing to their demise, only this study quantifies how much time they may have left, said Seth Riley, an NPS wildlife ecologist, associate adjunct professor at UCLA and senior author of the study.
• PHOTOS: Mountain lions in the Santa Monica Mountains may face extinction
The lions are isolated from other lions in neighboring wildlands by the 101 Freeway, eight to 10 lanes of some of the heaviest traffic in the United States. Because of the freeway, lions from the north in the Simi Hills, Santa Susana Mountains and Los Padres National Forest don’t ever reach them, causing limited breeding opportunities. Often, the two males in the group mate with their own offspring, resulting in dangerously low genetic diversity that can lead to poor health and extinction, Riley said.
“We have worked for years with our partners to increase connectivity across the 101 (Freeway) 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,” Riley said.
Scientists compared the L.A. lions with a group of Florida panthers (panthers and mountain lions are the same species) that nearly went extinct due to low biodiversity, a condition known as inbreeding depression. The Florida lions developed holes in their hearts and the males became sterile. Overall, the population was weaker and more susceptible to disease, Riley explained. Florida brought in eight panthers from Texas and the population rose from 25 to 200, Riley said.
While that is a possible solution in L.A., Riley said the scientists hope something else could be done sooner to increase biodiversity of the mountain lions in the Santa Monica Mountains.
One option is to build a wildlife overpass over the 101 Freeway and side road for the lions, as well as bobcats and other critters who want to connect with more of their own kind to the north.
• RELATED STORY: First public comments are tonight for proposed freeway crossing to aid mountain lions
The so-called Liberty Canyon Wildlife Crossing would cost about $50 million and is the subject of the National Wildlife Federation’s “Save L.A. Cougars” fundraising effort, Riley said.
“So we can look to what happened to Florida panthers as a cautionary tale,” said lead author John Benson, a wildlife ecologist at UCLA.
Benson said aside from Florida and the mountain lions in the Santa Monica Mountains, cougars in the Santa Ana Mountains in Orange County also have some of the lowest genetic diversity documented. Riley said UC Davis and UCLA scientists may focus their next study on Orange County mountain lions.
But the Santa Monica Mountains population may not be doomed. With the introduction of just one new lion every 2 1/2 years, the possibility of extinction drops dramatically, Riley said.
He said reproductive and survival rates are “pretty good” despite their isolation, a testament to the quality of habitat in the Santa Monica Mountains National Recreation Area. But the prognosis will get worse as time goes on and genetic isolation worsens.
While some have crossed the 101 Freeway, many don’t make it alive. One lion successfully crossed the 101, the 118 and the 126 but got hit by a car and died while trying to cross the 5 Freeway, Riley said. It most likely was running from another male mountain lion, he said.
“It is amazing we still have mountain lions in Los Angeles,” Riley remarked.
