Nature and Biodiversity

Los Angeles wants to build a bridge across a busy highway to save its mountain lions

Light falls across the face of a mountain lion that had given birth a month ago to two cubs at the Venezuelan Zoo in Caracas.  Light falls across the face of Mariela, a mountain lion that had given birth a month ago to two cubs, Adan and Eva, at the Venezuelan Zoo in Caracas August 18, 2005. REUTERS/Howard Yanes PP05080156 - RP6DRNATAHAB

Scientists say a new wildlife bridge may be the only way to prevent the extinction of LA's cougars. Image: REUTERS/Howard Yanes PP05080156 - RP6DRNATAHAB

Douglas Broom
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He’s Hollywood’s lonely lion. P22 – as he’s known to wildlife rangers – is a young male mountain lion who has made his home on a Los Angeles hillside under the iconic Hollywood sign.

P22 has a GPS radio collar so rangers can track his movements around Griffith Park, a wild area in the heart of the city. He’d already proved his survival skills by crossing two highways to reach his new refuge. Eighteen other mountain lions have died trying to cross roads since 2002.

Image: National Park Service

Although badly affected by rat poison when he was first captured in 2014, P22 has since recovered and is reported to be living on a diet of deer, raccoon and coyote. He was recently recaptured to replace the battery in his tracker and found to be healthy.

Image: National Geographic

The rest of Los Angeles’ big cats, also known as cougars and pumas, are trapped in the Santa Monica Mountains, cut off by busy roads and urban development. Scientists say a new wildlife bridge may be the only way to prevent their extinction.

A bridge to freedom

The $60 million Liberty Canyon Crossing will also help deer and other large mammals trapped in the mountains by Los Angeles’ sprawling suburbs and the 10-lane US 101 highway.

Due for completion in 2023, the bridge will be planted with local vegetation to give the mountain lions cover as they cross. It’s currently at the design and engineering stage and is being supported by, among others, the Boeing and the Leonardo DiCaprio Foundation.

Image: Save LA Cougars

There are thought to be around 50 mountain lions in and around the Santa Monica Mountains. Isolated from neighbouring groups, they are suffering the effects of inbreeding and environmental changes such as wildfires and fewer prey species.

Scientists predict that if the population is unable to escape and interact with other lions it could become extinct within 50 years. Mountain lions need lots of space – naturally solitary, an adult male can range over huge areas looking for food.

All creatures great and small

Wildlife crossings have been built all over the world. The Netherlands has 600 bridges and tunnels, including the Natuurbrug Zanderij Crailoo near Hilversum. The “ecoduct” spans a rail line, a river, business park and sports complex.

Image: Park Australia

Australia’s Christmas Island helps guide millions of red crabs safely across roads on their way to their spawning grounds every year. In Japan, rail tracks have U-shaped recesses to stop turtles being crushed by rail switches.

Wildlife crossings can save human as well as animal lives, too. In the US, as many as two million large animals are hit by vehicles every year. Collisions with deer, for example, result in 200 human deaths. The cost of these accidents is put at $4 billion a year.

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