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Santa Monica Mountain Lions May Go Extinct Because They're Trapped By Freeways, Says Study

An adult male mountain lion in the Santa Monica Mountains. (Photo by National Park Service via the Creative Commons on Flickr)
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We've long known that the Santa Monica mountain lion is in danger; they're trapped in a virtual prison because their environment is bordered by the sea and the 101 and 405 freeways. This means that inbreeding is not uncommon among them. Now, a report says that the situation is just as dire as researchers had feared; there's a 99.7% chance that they will go extinct if we don't do anything about it, the National Parks Service said in a release.

The research paper, published on Tuesday in Proceedings of the Royal Society B, is a joint study between researchers from the National Park Service, UCLA, UC Davis, and Utah State University. The paper said that the population of mountain lions is actually doing OK at the moment, but it will likely face a steep decline over the next 50 years if there's no way for them to branch out of the region they're stuck in. If nothing changes, it's almost a guarantee that we won't see the mountain lions anymore. Researchers pointed to the example of the Florida panthers, who'd faced a similar plight.

The Santa Monica mountain lion "has the lowest genetic diversity documented for mountain lions aside from Florida panthers," said Dr. John Benson of UCLA. Benson is the lead author of the study. "So we can look to what happened to Florida panthers 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."

Why, exactly, is inbreeding bad? When lions keep mating with close relatives, this paves way for a lower genetic diversity, which then leads to the aforementioned "inbreeding depression." No, it's not something that you can slap some Zoloft on. What inbreeding depression means is that the species becomes more vulnerable, less robust. In an interview with KPCC, Benson said that it "can manifest in unpredictable ways. And ways that have been shown are: higher susceptibility to disease, male reproductive problems including low sperm counts, and heart defects."

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The solution—one that the National Park Service has been touting for a few years—is for Caltrans to build an overpass that goes over the 101 freeway near Agoura Hills, connecting the Santa Monica Mountains with the Simi Hills and Santa Susana Mountains. The project is expected to be privately financed, and its advocates have their work cut out for them: they'll need to raise $10 million by early 2017 to stay on track with Caltrans' timetable for the project, but so far they've only raised $1.2 million. The National Wildlife Federation has started a #SaveLACougars initiative to raise funding.


A rendering of the proposed wildlife overpass above the 101 Freeway near Liberty Canyon Road in Agoura Hills. (Resource Conservation District)
You might be saying: Why can't we just introduce more mountain lions into the Santa Monica Mountains? As Benson explained to KPCC, it's impractical (i.e. $$$) to get and transport mountain lions into the area. Also, the bridge idea would benefit a whole array of different animals in the region (like bobcats and even birds), not just mountain lions.

As we've seen in the past, individual animals are sometimes able to break out of the Santa Monica Mountains, though these incidences are uncommon. Everyone's favorite cat, P-22, is believed to have crossed the 405 freeway to end up in Griffith Park. Also notable is a black bear who'd broken into the Santa Monica Mountains earlier this month; it's hypothesized that it may have crossed the 118 and 101 freeways to get into the region.

If you need a little nudge to make a donation to #SaveLACougars, here's Rainn Wilson explaining why the initiative is vital: