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.
- 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
- 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.
- 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.