A Riverside County mountain lion sired 11 kittens, but that won’t fix weak gene pool

Seven male cougars have crossed Interstate 15 near Temecula over the last 15 years, and one sired 11 kittens. Wildlife biologists are heartened by this because it demonstrates that a single male can enhance genetic diversity among inbred cougar populations.

The fact that only one managed to reproduce, however, also shows how tough it is to diversify the gene pool in the small, isolated populations of mountain lions remaining in the Santa Ana Mountains, according to a study published in May in the online journal Royal Society Open Science.

Now the research team led by Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center, is proposing a “puma conservation network” along a 2-mile stretch of the freeway, comprised of wildlife corridors, bridges and improvements in underpasses currently occupied by homeless camps.

An estimated 20 mountain lions currently prowl the Santa Ana range, a landscape fragmented by development and highways.

Vickers said there are a number of ecological reasons to protect the big cats.

“Removing the top predator could have serious cascading effects all the way down the food chain to birds and plants,” he said. “Mountain lions help control populations of deer, coyotes, raccoons and other species.”

“From the human perspective,” he added, “increasing numbers of deer could potentially lead to more collisions with vehicles.”

Mountain lions are not threatened or endangered in California, but they are legally classified as a “specially protected species” by the California Department of Fish and Wildlife. The statewide population of about 6,000 is relatively stable.

One of the largest mountain lion populations in Southern California is confined within 275 square miles in and around the Santa Monica Mountains National Recreation Area, which is bordered by the Pacific Ocean, major freeways, housing and commercial developments and agricultural fields.

Studies suggest that that terrain, which is bisected by Interstates 405 and 101, may have reached its carrying capacity with two or three adult male lions, four to six females and some kittens. Inbreeding is a serious problem among these big cats, which have extremely low genetic diversity.

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Jeff Sikich, wildlife biologist with the National Park Service, walks a trail in Griffith Park near the observatory to access remote cameras used to monitor possible activity by mountain lion P-22. Sikich and his team captured and radio-collared the lion near Griffith Park on March 28, but the GPS has stopped functioning.   (Al Seib / Los Angeles Times)

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Jeff Sikich, wildlife biologist with the National Park Service, uses a radio receiver near Griffith Park to monitor possible activity by mountain lion P-22. Sikich is using radio telemetry to monitor P-22 and hopes to recapture the lion to attach a new GPS.   (Al Seib / Los Angeles Times)

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Biology tech Matt Whitmire, left, secures a remote camera as wildlife biologist Miguel Ordenana, right, both of Cooper Ecological Monitoring, surveys the area as they check one of several remote cameras aimed at a possible wildlife corridor in the Cahuenga Pass.   (Al Seib / Los Angeles Times)

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Daniel S. Cooper, president of Cooper Ecological Monitoring, crosses the Mulholland Drive Bridge over the 101 Freeway through the Cahuenga Pass. Cooper believes the bridge may have been the route taken by mountain lion P-22, who managed to cross both the 405 and 101 freeways to reach Griffith Park. Cooper Ecological Monitoring places remote cameras on potential wildlife corridors for the Griffith Park Wildlife Connectivity Study to evaluate the movement of mammals through the corridors that may connect Griffith Park to neighboring natural areas.  (Al Seib / Los Angeles Times)

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Jeff Sikich, wildlife biologist with the National Park Service, adjusts the infrared trigger used on remote cameras in Griffith Park to monitor possible activity by mountain lion P-22.  (Al Seib / Los Angeles Times)

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Daniel S. Cooper, right, president of Cooper Ecological Monitoring, checks a remote camera at Tunnel 6, which goes under the 134 Freeway and is used by equestrians, in Griffith Park. Cooper is monitoring possible access routes of mountain lion P-22, who successfully crossed both the 405 and 101 freeways to reach Griffith Park.   (Al Seib / Los Angeles Times)

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Jeff Sikich, wildlife biologist with the National Park Service, walks a trail in Griffith Park near the observatory to access remote cameras used to monitor activity by mountain lion P-22, who scientists believe crossed both the 405 and 101 freeways to access one of the largest municipal parks in the country.  (Al Seib / Los Angeles Times)

“In Southern California, we have different mountain ranges — the Santa Monicas and Santa Anas — where lion populations are separated by freeways,” Vickers said. “Enabling lions to cross the freeways safely could help these struggling populations stave off extinction.”

On Wednesday night, a mountain lion was struck and killed while attempting to cross I-15 near the Temecula Creek bridge, Vickers said.

Louis.Sahagun@latimes.com

Twitter: @LouisSahagun