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Climate and Environment

What We've Learned In The 20 Years We've Been Tracking Mountain Lions In The Santa Monicas

A cougar photographed using a night camera
P-35, a female mountain lion, is photographed in the Santa Susana Mountains.
(Courtesy National Park Service)
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Here's some trivia for you:

Did you know that Los Angeles is one of only two megacities in the entire world where people and big cats like pumas can share a zip code? (the other is Mumbai, India if you're wondering.)

It's been 20 years since the tagging of P-1, the first mountain lion in the Santa Monica Mountains to be tracked through a GPS collar.

So two decades — and about 100 mountain lions later— we're checking in on what we've learned about cougars with Seth Riley, a wildlife ecologist with the National Park Service.

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Here's what we asked, and what he had to say.

[Note: edited slightly for clarity.]

Mountain lions are pretty low profile neighbors most of the time, they don't really want to let you know that they're there. Tell us how many are here in L.A. and where do they live?

The population, as you said, that we've been studying is in the Santa Monica Mountains to the north and west of Los Angeles. And from all the work we've done over these 20 years, we've come to understand there's only room for about 10 to 12 adults and sub adults in the Santa Monica Mountains. There are other areas around Los Angeles that they live as well, down to the south in the Santa Ana Mountains and in the San Gabriels and San Bernardinos. [Our focus has been] in the Santa Monicas.

A map of the L.A. coastal area is dotted with different colors showing movement of mountain lions.
Each color represents the movements of a different mountain lion (P-1 through P-22) tracked via GPS from the start of research in 2002 through December 2013.
(Courtesy National Park Service)

So why was it important to start collaring and tracking their movements? And what have we learned in that time?

We didn't even really know that there was a resident reproducing population of mountain lions in the Santa Monicas before 2002, when we started this work.

Mountain lions are really the ultimate challenge for conservation in a fragmented urban landscape like ours. And so they really give us a lot of information about what's going on with wildlife. What are the potential impacts of urbanization and fragmentation. And one of the things that they've been especially valuable to learn about from them is, to what extent natural areas like the Santa Monicas are connected to other natural areas, and how much of a barrier things like freeways and development are.

The Santa Monicas are really isolated by the 101 Freeway, from all other natural areas to the north. And that's been one of the things that we've learned. That's a huge issue. The positive news from the beginning that we've seen through all of our tracking is that the population is reproducing, and survival is pretty good for the most part. They're staying out of people's way, the vast majority of the time, which is good...very few conflicts with people. But the [area] is just not big enough for a viable population in the long run, genetically.

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We're talking about issues with inbreeding affecting their ability to be healthy when they reproduce. Is that right?

Animals are reproducing with close relatives. So we've been able to follow individual animals through the tracking and see that males are mating with their daughters and granddaughters and, and even great granddaughters, and that's bad for the genetic diversity.

And then we've seen that very few animals are able to disperse —especially younger animals are not able to disperse — out of the Santa Monicas, and that contributes to that close inbreeding and the lack of genetic diversity overall. We've also started to see actual physical signs of that inbreeding. So things like kinked tails and a male with only one descended testicle. Things that were being seen in Florida panthers, for example, in the mid 90s, when they almost were lost because of inbreeding effects.

We recently lost two collared Pumas. P-89 who was fatally hit on the 101 Freewaythis month and P-54 in Juneon Las Virgenes Road near Malibu Creek State Park.

It's just so sad when that happens. But it's a symptom of us developing around their habitat. So I'm hoping you could tell us about this huge wildlife crossing that's in the works in Agoura Hills, and how that might help mountain lions survive by avoiding cars and avoid inbreeding.

In this case, [our] research [over the last 20 years] has really turned into conservation action and we have this wildlife crossing going in in the Agoura Hills area. It's really exciting. It's going to reconnect these natural areas the Santa Monica has to the Simi Hills, and it's going to be valuable for everything, all kinds of wildlife, but especially important for mountain lions, because they have the smallest population and definitely one that's at risk.

Eleven animals, a coyote, deer, rabbit, mountain lion, bobcat, eagle, bat, toad, aunt, and lizard, are depicted in circles around a depiction of the wildlife crossing.
A breakdown of the some of the biodiversity of wildlife that would benefit from the crossing.
(Living Habitats/National Wildlife Federation)

We've actually had five different animals that we've been tracking that have died this year already, including four that have been hit by cars. And to some extent, that's just an anomaly. But it's tough when you have a relatively small population, and roads are definitely an issue.

Really the biggest issue is this separation of the populations from the roads. And so it's going to allow animals to disperse out of the Santa Monicas, but most importantly bring new genetic material in.

What questions do you have about Southern California?