Los Angeles’ fabled mountain lions are taking greater risks following the catastrophic Woolsey wildfire in 2018, which destroyed much of their habitat

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 a living in the wooded LA-area hills.

Now, researchers have found that wildfires, and specifically the 2018 Woolsey fire, are putting the LA mountain lions’ future in more doubt.

Rachel Blakey, 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 behaviours that would put them at risk of negative encounters with humans and other mountain lions.

“These risky behaviours indicate the ongoing negative effects of a large fire disturbance in a population already grappling with the multiple stressors of living within a megacity.”

See also: Nitrous oxide levels in atmosphere could soar after wildfires

mountain lion habitat

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, including Seth Riley, Jeff Sikich and Daniel Blumstein, 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.

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 four 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 travelling almost 400km per month on average, up from 250km 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.

One habit that didn’t change was the mountain lions’ strong tendency to avoid heavily populated urban areas.

After the fire, the mountain lions continue to spend only 4-5% of their time in urban areas.

Blakey added: “The idea that mountain lions will run across freeways, rather than take their chances in urban areas, really reinforces how strongly mountain lions avoid humans.

“I think this is an important point, because people who live in the urban-wildland interface often worry that large disturbances like this could increase human-wildlife conflict.”

Los Angeles’ wildlife crossing

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.

The findings also highlight the increasing importance of connecting natural habitats in urban areas to help mountain lions and other wildlife access resources and breeding partners, something that is happening in LA.

Blakey said: “We are lucky that, thanks to decades of science by the National Park Service and tireless campaigning by the National Wildlife Federation, our mountain lion population in LA will soon receive a much-needed boost to their connectivity via the Wallis Annenberg wildlife 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.

The research is published in Current Biology.

Image: A mountain lion above Los Angeles. © National Park Service.