Mountain lions outside Los Angeles take more risks after wildfire

In the 15 months after the Woolsey fire in Los Angeles, mountain lions were more likely to cross busy roads, travel further and move around during the day, putting the already vulnerable group of cats at increased risk

By Corryn Wetzel

After a 2018 wildfire razed areas of the woods where they live near Los Angeles, mountain lions crossed major roads more often

US National Park Service

After a 2018 wildfire, mountain lions near Los Angeles, California, were more likely to cross roads, travel further and be active during the daytime – when encounters with people are most likely. The shift to bolder behaviour concerns researchers, who note increasing wildfires may jeopardise the urban cats’ future.

The wooded Santa Monica mountains north of Los Angeles are home to around 100 mountain lions, which, despite being bordered by large highways and human development, have managed to survive by hunting mule deer.

“This [mountain lion] population is really special, not just because it’s very much beloved of the people… but because it’s a population that’s very much at risk,” says Rachel Blakey, now at Cal Poly Pomona in California.

This unique group of cats has been studied for two decades and many of the animals are continually tracked with GPS and activity monitor collars. After the 2018 Woolsey fire scorched more than 400 square kilometres of land – roughly half of the cats’ habitat – researchers compared movement data from 17 mountain lions before and after the blaze.

They found significant differences in the mountain lions’ behaviour after the fire. In the 15 months following the blaze, the cats’ average number of road crossings jumped from three to five per month, and their monthly distance travelled increased from 250 kilometres to 390 kilometres. The mountain lions were also more likely to come into close contact with other mountain lions, which can lead to fighting between the solitary cats. The researchers believe these changes probably reflect their desire to stay away from other mountain lions and a desperation to find and hunt food without the camouflage of vegetation.

“The size and location of this fire really lent itself to asking some of those bigger questions about the interaction of fire and urbanisation,” says Megan Jennings at San Diego State University in California, who was not involved in the work. “It’s nice to have that confirmation and understanding of what’s happening, so we can better take action on it.”

Because there have been more wildfires in the area in recent years, the discovery underscores the value of corridors and highway overpasses that could help local mountain lions and other local wildlife move and hunt safely.

Journal reference: Current Biology, DOI: 10.1016/j.cub.2022.08.082

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