Although the mountain lion population in the Santa Monica Mountains is robust, the isolation caused by urban development and freeways could lead to the animals’ extinction over the next 50 years, according to a study released Tuesday.
The study found that the isolation will lead to a rapid decline in genetic diversity, which could affect the lions’ ability to reproduce, something known as “inbreeding depression.”
“The Santa Monica Mountains population, along with the one in the Santa Ana Mountains in Orange County, has the lowest genetic diversity documented for mountain lions aside from Florida panthers,” according to John Benson, a wildlife ecologist with the La Kretz Center for California Conservation Science at UCLA and lead author of the study. “So we can look to what happened to Florida as a cautionary tale. When their genetic diversity reached very low levels in the 1990s, panthers nearly went extinct due to factors associated with inbreeding depression.”
The study, performed by researchers from the National Park Service, UCLA, UC Davis and Utah State University, used a population-viability model, which predicted a 99.7 percent chance of extinction of the Santa Monica Mountains lions. But researchers found that even a minimal introduction of new lions to the area — a small as one new lion every two to four years — could maintain the strength of the population.
One possible way of addressing that issue would be a proposed wildlife crossing across the Ventura (101) Freeway that would allow lions from the north to cross into the Santa Monica Mountains, according to the report.
Researchers noted that a male lion known as P-12 became the only known lion to cross the freeway from north to south in 2009. He eventually began breeding, creating some diversity in the population, but he subsequently mated with two of his offspring and a granddaughter, contributing to the inbreeding problem.
According to the study, a wildlife crossing over the freeway would help lessen the problem of inbreeding by allowing offspring born in the Santa Monica Mountains to disperse to the north.
“Fifty-plus years ago when the 101 Freeway was built, no one was thinking about wildlife connectivity,” said National Park Service wildlife ecologist Seth Riley, 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.”
–City News Service