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Experts Say Southern California Mountain Lions Could Become Extinct in 50 Years

Mountain Lion looking at camera | Photo: Ben Masters, iStock
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Two of Southern California's tiny mountain lion populations are at risk of becoming extinct in as little as 50 years unless humans act to build bridges and trails to connect their habitats, a study released Wednesday said.

As little as 30 adult mountain lions – 20 in the Santa Ana Mountains stretching through Orange, Riverside and San Diego counties; and 8 to 10 in the Santa Monica Mountains in Los Angeles County –  live the ranges today, but could vanish because their ability to travel and mate are cut off by freeways, housing developments and humans, said T. Winston Vickers, the report's co-author and associate veterinarian at the University of California, Davis’ Karen C. Drayer Wildlife Health Center.

"This study gives us a much better idea of how quickly we need to take action – and it’s like yesterday," Vickers told SoCal Connected.

For years, wildlife experts have studied the mountain lion populations in Southern California, encouraging lawmakers to build such bridges and other means for the cats to navigate to prevent them from potentially deadly attempts to cross busy freeways and for mating. A proposed bridge across the 101 Freeway in Agoura has an expected price tag of $60 million. Vickers said about $7 million has been raised.

Mountain lions face numerous obstacles for survival – including the recent wildfires and drought, a lack of prey, and traffic, but the latest study focused extensively on genetics. Although the study is similar to past reports that proposed bridges and explained the dangers of inbreeding, the new findings reveal how dire the problem is and how soon it could wipe out the local species.

Capturing lions from babies to adults and examining their DNA, wild life experts believe inbreeding among the small numbers of mountain lions will cause genetic diversity in the populations to rapidly decline during the next five decades. The declining gene pool will result in changes in semen quality, physical problems including heart defects and cleft palates, and a reduction in kitten survival rates, Vickers said.

When the researchers examined the effects of what they call "inbreeding depression," their data predicted that quick extinction was almost certain.

"If you had fewer and fewer animals on the landscape, it becomes harder and harder for them to find mates," Vickers said. "At some point, poor reproduction starts to cause even less reproduction, difficulties of finding mates and getting into a vicious spiral."

Mountain lions in the Santa Ana ranges from Chino Hills to Fallbrook are particularly at risk because Interstate 15 cuts their ability to roam. The animals seeking out unprotected livestock through the corridor to eat face being struck by vehicles in attempts to cross the freeway, the study said.

Wildlife experts are working with engineering students at Cal Poly Pomona on designs to create a natural path under the highway at the Temecula Creek Bridge. The crossing, however, is "badly impacted" by noise and light from the highway, as well as human taggers, that scare off the lions.

In the Santa Monica Mountains, plans have been in the works for years to build the bridge over the 101 Freeway, where scientists’ studies have determined some mountain lions have safely made it across.

Vickers said mountain lions are capable of walking hundreds, even thousands of miles.

The loss of mountain lions could have a significant effect on the local ecosystem, Vickers said. The animals’ occasional maneuvers into residential neighborhoods in search of food or small pets might give residents a scare, but their lives in the local forests help to control the deer and coyote populations, as well as birds and other small animals. 

"There’s this inherent belief in the value of having a system that’s as balanced as possible in the way it evolved in the first place and recognizing that we should, where we can, avoid disrupting it too much," Vickers said.

The study concluded the mountain lions can be saved, but protecting lands, linking their habitats, and developing strategies are necessary for them to coexist with humans. Vickers said those behind the study recognize it’s important to get the public’s backing before any significant amounts of taxpayer dollars should be spent. Mountain lions reside in lands under both government and private control.

"This has been talked about for so long that there is a lot of support from wildlife agencies and some of the nonprofits," he said. "There is clearly support for some improvements. There are funds that could be tapped at the state level down the road."

Without the expensive projects, wild life officials also could consider "translocation," physically capturing some lions and moving them to other areas to mate, Vickers said.

The study was led by John Benson at the University of Nebraska, assisted by Vickers and co-authors at UCLA, the National Park Service, the University of Washington, Northern Arizona University, and the University of Wyoming. UCLA’s  La Kretz Center for California Conservation Science, and the National Park Service provided funding.

Top Image: Mountain Lion | Ben Masters/iStock

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