Synopsis of Big Cats in the City: WildFutures Webinar about Los Angeles Mountain Lions

A mountain lion in the Verdugos Mountains, with the city of Los Angeles visible in the background. Verdugos Mountain Lion by the National Park Service. CC BY 2.0


On May 15, I tuned into a webinar hosted by WildFutures: a project of Earth Island Institute which uses science and the media to challenge negative perceptions of large carnivores. The title of the webinar was Big Cats in the City: Ecology, Behavior, and Conservation of Mountain Lions around Los Angeles.

With nearly 180 people in attendance, Big Cats in the City was a popular webinar. Dr. Seth Riley, a wildlife ecologist for the National Park Service (NPS), was the presenter.

For the past 18 years, Dr. Riley has worked at the Santa Monica Mountains National Recreation Area on the outskirts of LA. He has been investigating the effects of roadways and urbanization on mountain lions (Puma concolor), and on May 15 he shared a little of what he had learned.

Below is an overview of some of the key points Dr. Riley discussed in Big Cats in the City.

A park ranger giving a safety talk to schoolchildren in the Santa Monica Mountains National Recreation Area. Safety Talk by the National Park Service. Public Domain.



  • Los Angeles is one of only two megacities to host a population of big cats: the other being Mumbai with leopards.
  • The National Park Service began studying carnivores in the Santa Monica Mountains in 1996 because they need considerable space to survive. Large carnivores are, in certain regards, the “ultimate conservation challenge.”
  • The NPS has specifically studied mountain lions in the Santa Monicas since 2002.

LA’s Lions Need More Room

If LA’s mountain lions are to persist into the future, they need a wildlife overpass over Highway 101. Here is an example of a wildlife overpass in Canada. Trans-Canada Wildlife Overpass by Qyd. CC BY 2.5
  • There is only room for 10-15 adult and subadult mountain lions in the Santa Monica Mountains Recreation Area.
    • This is not enough to maintain the cats’ genetic viability.
    • To compound the problem of limited space, much of the land within the Santa Monicas is privately owned. This is producing development pressures and habitat fragmentation inside the park.
  • Highway 101 acts like a barrier on the northern edge of the Santa Monicas: preventing mountain lions from moving into and out of the park.
    • This is leading to high levels of inbreeding, which will eventually compromise the ability of LA’s mountain lions to survive. There have been four documented father-daughter matings.
    • The inability of subadult males to disperse out of the Santa Monicas is also provoking more intraspecies (within species) fighting. Out of 20 males born since 2002, 43% have been killed in such conflicts.
  • If LA’s mountain lions are to survive, they need to be able to cross the 101.
  • For this reason, the National Park Service and concerned citizens want to build a wildlife overpass over the 101.
    • Dr. Riley and his colleagues have already identified the ideal spot for the overpass: Liberty Canyon. It features natural habitat on both sides of the highway.
    • Having 10 lanes of traffic, this would be the largest stretch of highway with a wildlife overpass.
  • The key hurdle to overcome for this overpass is money.

Anticoagulant Rodenticides

In March 2014, celebrity mountain lion P22 tested positive for anti-coagulant rodenticides. Here is P22 suffering from mange, possibly influenced by his exposure to rodenticides. He was successfully treated by the NPS for his mange, and fully recovered. P22 Mange by the National Park Service. Public Domain.
  • As in northern California, anticoagulant rodenticides are a major problem for mountain lions near LA.
  • Due to their position at the top of the food chain, mountain lions accumulate large amounts of these toxins.
  • 90% of tested mountain lions contained anticoagulant rodenticides in their bodies.
  • These toxins kill mountain lions and other wildlife by causing them to bleed to death internally.
  • Mountain lions P3 and P4 both died from anticoagulants.


The above section is a highly condensed version of what I considered to be the most important pieces of information from the webinar. Below is a recording of the entire presentation.


In Dr. Riley’s own words, it is “amazing” that we have mountain lions in Los Angeles. But if the cats are to persist, they need more room and reduced exposure to rodenticides. Donations to the Santa Monica Mountains Fund or the National Wildlife Federation can help with the crucial goal of building the Liberty Canyon overpass.

28 Thoughts

  1. I didn’t know there were mountain lions in Los Angeles! Though I’ve seen a documentary about the leopards in Mumbai. They feed on wild boars there, I believe.

    Liked by 1 person

    1. Well, the situation in Los Angeles is a bit different than Mumbai. In the latter city, the leopards live in a small national park in the heart of the city – and many of them were brought there by government workers. The mountain lions in Los Angeles live just on the outskirts of the city, and have been there since long before the city was.

      Yes, I’ve heard that the leopard in Mumbai largely feed on wild boars; I’ve seen footage of a mother leopard killing a piglet. They also traverse to city streets at night sometimes, preying on stray dogs. Apparently Mumbai has an abundance of stray dogs, and the leopards are actually providing a valuable service by reducing their population. It’s not all good though: people have been attacked and killed by Mumbai’s leopards. I don’t think there have ever been any attacks in LA, but I could be wrong.

      Liked by 1 person

  2. I’d hears about these mountian lions in school- a large number of big cats just outside of the city. Apparently they remain quite reclustive and are not often spotted relative to the human population. It is fascinating, also slightly sad. Two mountain lions were shot in Port Coquitlam this week- a city not far from Vancouver. Thank you for sharing.

    Liked by 1 person

    1. Yea, the LA lions seem to be very good at not being seen by people. In the webinar there is a photo of a mountain lion literally walking down an urban street: surrounded by cars and buildings. But it was night time, so I’m guessing no one saw it. Apparently most of the LA cats avoid built up areas, but a few are more willing to traverse them than others.


  3. Wow! Mountain lions are amazing creatures. I was surprised to hear that Los Angeles is one of two mega cities to have big cats! This was a very interesting post.

    Liked by 1 person

    1. Yea, a mountain lion got trapped in someone’s house a few years ago and made a big news story! But when people have him some space he got out of there as fast as he could.

      Mountain lions are incredible animals. But unless we can build the overpass over Highway 101 and reduce the cats’ exposure to poisons, Los Angeles may not have mountain lions in the not-too-distant future.

      Liked by 1 person

      1. Wow! I find it funny though how we, as humans, get annoyed when animals enter “our land” when we basically stole their habitats and destroyed them. I hope that overpass gets built despite the cost, it’s important to protect these animals!

        Liked by 1 person

    1. Thank you! There might not be any big cats in Australia, but you have an abundance of fascinating creatures that are found in very few other places – if any. You’re incredibly fortunate to live in such a unique continent.


  4. Thanks Josh for sharing our webinar. I love your website, by the way. Our next and last webinar in the 2018 Wildlfe Webinar Series, “Living with Mountain Lions in the Bay Area” is September 20th. We have other excellent wildlife webinars on our website. You call find them at, and navigate to webinar archives. For all things wild and free, Sharon Negri, Director, WildFutures

    Liked by 1 person

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