Mountain lions increase road crossings after wildfire

Conservationists have long warned that Southern California mountain lions could disappear within decades due to inbreeding and habitat loss. Now biologists have identified another threat that could hasten their demise – extreme wildfires.

In an article published Thursday in the journal Current Biology, UCLA researchers found that the 2018 Woolsey Fire greatly increased the likelihood of a mountain lion being fatally struck by a motorist or killed by another panther in a territorial dispute.

Mountain Lion P-65

Mountain Lion P-65.

(National Park Service)

The reason? Mountain lions were so eager to avoid the 100,000-acre burn zone that they chose instead to cross busy roads within the Santa Monica Mountains or enter the hunting grounds of other adult cougars.

The research paints a bleak picture of the mountain lion’s struggle for survival as evolution has increasingly limited and divided its habitat. There are also concerns about the potential effectiveness of a long-planned wildlife crossing aimed at allowing mountain lions safe passage across a 10-lane highway, in part to allow them to mate with cougars from other areas and increase genetic diversity.

The researchers found that in the 15 months after the fire burned from Ventura County’s Simi Hills to the beaches of Malibu, potentially fatal road and highway crossings by radio-collared mountain lions increased from three to five per month.

They also found that the distances the animals roamed had doubled – growing from 155 miles per month to 342 – greatly increasing the risk of deadly clashes between mountain lions in a shrinking range.

The UCLA study suggests that mountain lions’ behavioral changes likely stem from a complex tradeoff that balances the need to forage and breed for food against avoiding human encounters in the fire-scarred mountainous landscape.

A new study by UCLA researcher Rachel Blakey has found that mountain lions avoid 100,000 acres of burned habitat.

A new study found mountain lions avoided 100,000 acres of burned habitat after the 2018 Woolsey Fire and stepped up their dangerous road and highway crossings to avoid humans.

(Myung J. Chun / Los Angeles Times)

Ambush predators such as mountain lions, lynx, and African lions require the protection of dense native vegetation to successfully pursue prey and avoid territorial disputes, a leading cause of mortality among young cougars in the Santa Monica Mountains.

One habit that hasn’t changed, however, is the species’ strong dislike of densely populated urban centers. After the Woolsey Fire, the study found, mountain lions continued to spend only about 5% of their time in urban areas.

“The idea of ​​mountain lions running down highways instead of taking their chances in urban areas really reinforces how much mountain lions avoid humans,” said Rachel Blakey, lead author of the study.

“This is an important point,” she added, “because people living at the interface between city and wilderness often worry that large disturbances like the Woolsey Fire could increase the likelihood of conflicts with predators.”

But the change in behavior observed by the researchers could impede human efforts to control gene flow between the small, isolated populations of cougars trapped south of Freeway 101 in the Santa Monica Mountains and cougars trapped north in the Simi Hills and the Santa Susanna Mountains live to restore.

In particular, the proposed Wallis Annenberg Wildlife Crossing, which will cross the 101 Freeway at Liberty Canyon Road in Agoura Hills, is in the Woolsey burn scar.

Is it possible that mountain lions won’t use the 200ft long and 165ft wide bridge if they avoid the fire zone?

Seth Riley, Rachel Blakey and Jeff Sikich

UCLA researcher Rachel Blakey (center) is flanked by Seth Riley (left) and Jeff Sikich, both from the National Park Service.

(Myung J. Chun / Los Angeles Times)

“That’s a fair question,” said Seth Riley, a biologist at the National Park Service and co-author of the study. “We hope that doesn’t happen.”

To date, more than 5,000 individuals, foundations, agencies and corporations from around the world have donated more than $92 million to the project.

When completed in 2025, the bridge will be the largest and most expensive of its kind in the world – and the only one designed to save a species from extinction.

“All it takes is one mountain lion safely crossing the freeway every few years to trigger the kind of genetic spread they so badly need to survive,” Riley said.

Recent scientific studies suggest that the probability that Southern California mountain lions, which have the lowest genetic diversity documented for the species next to the critically endangered Florida panther, could become extinct in 50 years, is nearly 1 to 100% 4 exists.

The mountain lions’ heightened risk-taking following the Woolsey Fire adds to an already long list of threats.

P-54, a 5-year-old female mountain lion who was hit and killed by a vehicle on Las Virgenes Road in the Santa Monica Mountains earlier this year, was pregnant with four kittens. All five animals tested positive for rat poison, National Park Service biologists said.

P-54’s mother, P-23, was hit and killed by a vehicle on the same road in 2018. One of P-54’s descendants, P-97, was killed by a vehicle on the 405 freeway in April, the biologists said.

State officials concluded in 2020 that six isolated and genetically distinct cougar clans from Santa Cruz to the US-Mexico border form a subpopulation that could warrant listing as threatened under the state’s Endangered Species Act. Such a move could limit freeway construction and development to thousands of acres of land.

The move to list the clans as threatened followed a petition filed by the Center for Biological Diversity and the nonprofit Mountain Lion Foundation, which argued that the populations represent an “evolutionally important entity” that should be protected.

The California Fish and Game Commission is considering a final decision on this matter.

On Wednesday, Blakey, Riley and Jeff Sikich, an expert on the Santa Monica Mountains National Recreation Area’s mountain lions, stood on a ridge and looked out over steep slopes, valleys, oak forests and chaparral still recovering from the Woolsey Fire.

Using a telemetry antenna, they detected the pings of two radio-collared survivors roaming in the distance just a few kilometers apart: a male and a female mountain lion.

“It’s an incredible privilege,” Blakey said, “to live alongside these predators in Southern California.”

https://www.latimes.com/environment/story/2022-10-20/mountain-lions-increase-road-crossings-after-wildfire Mountain lions increase road crossings after wildfire

Alley Einstein

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