World’s Largest Wildlife Crossing Will Save Mountain Lions

Annemarie DonkinBy Annemarie Donkin      May 14, 2021

Share Story on:

World’s Largest Wildlife Crossing Will Save Mountain Lions
The proposed Liberty Canyon Wildlife Crossing—a wide, vegetated bridge spanning the Ventura (101) freeway in Agoura Hills—will allow wildlife such as mountain lions, bobcats, gray foxes and mule deer to cross safely from the Simi Hills into the Santa Monica Mountains to find food, new habitats and potential mates. With the recent discovery of a strong, young male mountain lion (P-95) in the Santa Monica Mountains, decades of planning and a steady stream of donations, the proposed Liberty Canyon Wildlife Crossing is fast becoming a reality. This is good news, since there is a need to build the crossing sooner rather than later. The National Park Service (NPS) reports that 23 mountains lions have been struck and killed by traffic in their study area since 2002. According to Wildlife Biologist Jeff Sikich, area mountain lions and bobcats are struggling to survive due to urban development and genetic inbreeding that results from wildlife being unable to cross the highway and roads to find suitable mates. These felines are in desperate need of access to the natural areas on both sides of US Route 101. Bridging the Divide Project leaders recently released a new design and cost estimates for the 165-foot-wide and 200-foot-long overpass that would cross 10 lanes of the 101 Freeway at Liberty Canyon in Agoura Hills and a 54-foot-wide crossing over Agoura Road. If the project stays on track with fundraising efforts, the $88 million crossing will break ground in late 2021 with an estimated completion by the end of 2023. The Liberty Canyon location was chosen by experts for a number of reasons, but mostly because there is publicly owned and protected land on both sides of the freeway that will never be developed. A crossing will also allow a wide variety of native wildlife including bobcats, deer, raccoons, frogs and even butterflies, to access connected open space and a wider diversity of mates. According to wildlife crossing designers, Living Habitats, an architectural landscape company based in Chicago, to reconstruct the natural topography the bridge would be covered with native vegetation and even mushrooms to create an ecologically resilient and more attractive wildlife passageway between the Santa Monica Mountains and the Simi Hills to the north. Native plants will also form a vegetated sound wall as a significant light and sound barrier across a freeway that carries more than 300,000 vehicles per day.
Endangered Mountain Lions in a Dense City
On January 16, the National Park Service announced an important new addition to its mountain lion study—P-95.

“P-95 is a young puma—about one and a half years old—weighing in at roughly 90 pounds,” wrote Jeff Sikich of the National Park Service. Sikich is a wildlife biologist researching the impacts of urbanization and habitat fragmentation on mountain lions at Santa Monica Mountains National Recreation Area (SMMNRA) in Southern California.

“After performing a health check-up ‘from the bottom of his paws to the teeth in his head,’ NPS says he is in good health and, based on some chirping they overheard along with a quick glance, it appears he is traveling either with a sibling or his mother,” Sikich wrote. “As one of only two megacities in the whole world with big cats living in our city limits (the other being Mumbai, India), it is imperative that L.A. support these wonderous creatures by caring for the environment and considering their well-being in all our policies.’”

What most worries wildlife professionals is that inbreeding among mountain lions is widespread within the wildlife populations of the Santa Monica Mountains as they become increasingly genetically isolated. According to the National Wildlife Federation, a single male mountain lion uses about 100,000 acres of natural habitat, about the size of the entire Santa Monica Mountains. If mountain lions cannot move between natural areas, their population will not survive. It’s essential to keep open spaces connected and create new habitat links where needed.

In order to expand their territory, some mountain lions risk crossing the freeway and many have died trying—hence the urgent need for a safe and secure crossing for all species that will ensure the survival of wildlife and their habitats.

In 2016, during a public presentation at King Gillette Ranch to raise awareness, Dr. Seth Riley, Chief Wildlife Biologist with the National Park Service, passionately advocated for mountain lions and said the reduction of territory for mountain lions has resulted in inbreeding, territorial fighting, and a decrease in genetic diversity, the lowest in the world.

“At the moment, we don’t have any safe way for them to cross the freeway,” Riley said. “Mountain lions are the most vulnerable species in our parks.” He emphasized that, without the addition of a wildlife crossing, the ecological and environmental impacts on wildlife movement that resulted from the original construction of US Route 101 will persist.

Other wildlife experts agree that the mountain lions are in danger.

“The most serious threat to preserving the Santa Monica Mountains in perpetuity is habitat fragmentation,” wrote David Szymanski, Superintendent for the SMMNRA. “This happens when barriers separate chunks of habitat from each other. The Liberty Canyon Crossing will re-establish a portion of the connection between the Santa Monica’s and the Simi Hills. Our intent is that the crossing serves not only mountain lions, which need it most, but also coyotes, bobcats, lizards, and even some birds.”

Public-Private Partnership
The Wildlife Crossing is made possible due to a public-private partnership with the core of the partnership being Caltrans, the National Park Service, the Santa Monica Mountains Conservancy, the Resource Conservation District of the Santa Monica Mountains and the National Wildlife Federation.

If there is one key person most responsible for fundraising and publicizing the urgent need for the Wildlife Crossing it’s the irrepressible Beth Pratt, California Regional Executive Director, National Wildlife Federation (NWF) and Leader of the worldwide #SaveLACougars Campaign.

A dedicated environmentalist, Pratt is tireless in her pursuit of the preservation of all species, especially the endangered mountain lions of the Santa Monica Mountains. Pratt is the champion of superstar cougar P-22, who became world-famous due to the National Geographic photograph by Steve Winter in 2013.

As the superstar “poster cat,” P-22 crossed two major freeways to get to the Hollywood Hills and Griffith Park from the Santa Monica Mountains. To date, no other mountain lions in the study have survived the same journey. Hence the urgent need for the wildlife crossing at the US Route 101 freeway.

Because of the ongoing support thus far from the #SaveLACougars community, Pratt reports that the campaign has secured funding for the important work of Caltrans through the final design.

“Caltrans is on track. They are completing the blueprints in August; that’s happening,” Pratt said. “The total project cost in 2018 was $88 million, with an estimated construction cost at the time between $55-78 million. As we advance through design, we now have more information…and are looking at cost reductions wherever possible.” She added that she is confident that all of the money will be there when the time comes to break ground.

According to Pratt, the wildlife crossing experts are not just about “where can we save money,” but also consider “what is it going take to successfully get the wildlife across the road?”

The key to the design, Pratt said, is to allow the animals to feel secure while crossing.

“They have to have a wide walkway proportionate to the length, or they might turn around and not feel safe especially for this density of traffic,” she said. “We are guided by science. The design of a natural landscape will create a connected ecosystem.”

If all goes well as planned, the massive project will break ground by the end of the year.
For more information:

Saving Santa Monica Mountains Wildlife
“Overall, the world’s largest wildlife crossing will save endangered wildlife from crossing a dangerous, impenetrable freeway that has cut them off from vital habitat since 1960,” said David Szymanski, Superintendent for the SMMNRA. “Citizens and communities have done an amazing job over the past 60 years in ensuring the protection of lands within the mountains,” Szymanski continued. “All of this civic action has made the L.A. region one of only two world megacities (the other being Mumbai, India) that still have large carnivores living within them.”

Santa Monica Mountains National Recreation Area (SMMNRA) is the largest urban national park in the country, encompassing more than 150,000 acres of mountains and coastline in Ventura and Los Angeles counties. It comprises a seamless network of local, state and federal parks interwoven with private lands and communities. As one of only five Mediterranean ecosystems in the world, SMMNRA preserves the rich biological diversity of more than 450 animal species and 26 distinct plant communities.

The National Wildlife Federation and the Santa Monica Mountains Fund have established a fundraising initiative,, to raise funds for the engineering design and construction expenses. For more information:
Annemarie Donkin
      May 14, 2021

Share Story on:

May 14, 2021

Thinking Out Loud
News Feature
Health Trends
All Things Connected
Rude Interruptions
My Corner of the Canyon