Recent California wildfires put LA mountain lions’ future in doubt

Los Angeles is known for its movie stars and beaches. It’s also known for being one of only two megacities in the world that supports a population of big cats. Despite being surrounded by a vast network of busy freeways and over ten million people, mountain lions have somehow managed to eke out survival in the wooded LA-area hills. Now, researchers reporting in Current Biology on October 20 have found that wildfires, and specifically the 2018 Woolsey fire, are putting the LA mountain lions’ future in more doubt.

Rachel Blakey (@blakey_rachel) of the University of California, Los Angeles, said:

“We found that after a large fire, in a fragmented urban landscape, a population of mountain lions who were already at risk of extinction increased behaviors that would put them at risk of negative encounters with humans and other mountain lions. These risky behaviors indicate the ongoing negative effects of a large fire disturbance in a population already grappling with the multiple stressors of living within a megacity.”

Using GPS to track mountain lion movement after a fire

When the Woolsey fire scorched about half of the mountain lion habitat in the Santa Monica mountains, Blakey and colleagues at the National Park Service and UCLA, wanted to know what it meant for the big cats. To find out, the researchers used GPS location and accelerometer data for 17 mountain lions tracked both before and after the fire, part of a larger dataset collected by Riley and Sikich, who have been studying the population for over 20 years. And what they found isn’t encouraging.

After wildfire, mountain lions avoided burned areas, they report. They also more often put themselves at risk by crossing roads, including freeways. In the 15 months after the fire, they crossed roads five times a month on average compared to three times before the fire. Furthermore, their rate of crossing the 101, a busy 10-lane freeway, increased after the fire from once every two years to once every 4 months. They also started moving around more often during the day, a habit that makes them more likely to cross paths with people.

The mountain lions were traveling almost 400 kilometers per month on average, up from 250 kilometers per month on average before the fire. Those increased distances the mountain lions needed to travel to find essential resources put them at more risk of skirmishes with other mountain lions.

Can the Wallis Annenberg wildlife crossing mitigate the problem?

Wallis Annenberg Wildlife Crossing conceptual drawing

The findings show that wildfires are putting mountain lions at more risk as their habitat and resources have shrunk and they’re forced to take greater risks to get by. She notes that the findings highlight the increasing importance of connecting natural habitat in urban areas to help mountain lions and other wildlife access resources and breeding partners. The researchers are encouraged by the groundbreaking earlier this year of the Wallis Annenberg wildlife crossing, soon to be the largest wildlife crossing in the world.

“We are lucky that our mountain lion population in LA will soon receive a much-needed boost to their connectivity via the Wallis Annenberg wildlife crossing.”

The Wallis Annenberg Wildlife Crossing is a vegetated overpass spanning the Ventura Freeway and Agoura Road under construction at Liberty Canyon in Agoura Hills, California. The bridge will be one of the largest urban wildlife crossings in the United States, connecting the Simi Hills and the Santa Monica Mountains over a busy freeway with ten traffic lanes, when including exit lanes.

The crossing is situated along a wildlife corridor within the Santa Monica Mountains National Recreation Area that consists of thousands of acres of local, state and federal protected lands and stretches northerly from Los Angeles into Ventura County.

To encourage use by wildlife, the bridge will have lush but drought-tolerant vegetation with matte materials to deflect bright headlights and insulation to quiet the roar of cars. Fencing at each end will help funnel them onto the crossing.

The hope is that the new crossing will help support and maintain genetic diversity in a broad range of species, including mountain lions. Other important steps for protecting the LA mountain lions and the environment at large include reducing car use, increasing green space, and avoiding wildfires started by people.

Image Credits

In-Article Image Credits

Wallis Annenberg Wildlife Crossing conceptual drawing via Annenberg Foundation with usage type - Editorial use (Fair Use)
Mountain lion above LA via National Park Service with usage type - Creative Commons License