‘Largest Wildlife Crossing in the World’ to Break Ground in California on Earth Day

While the population of mountain lions in the Los Angeles area is stable, they face threats to their longterm outlook. This is largely due to habitat loss and fragmentation caused by development and roads. A large project aiming to address this issue is about ready to break ground.

The National Wildlife Federation has announced that a groundbreaking ceremony for a wildlife crossing above U.S. 101 near Los Angeles has been scheduled for Earth Day, April 22. The largest wildlife crossing in the world, as it’s been billed, aims to ensure that animals like mountain lions can migrate more freely amid the urban sprawl. Those behind the project say it will make it easier for species in the Santa Monica Mountains to access food and potential mates.


Beth Pratt, regional executive director with the wildlife federation, says, “Crossings like this are nothing new. This one’s historic because we’re putting it over one of the busiest freeways in the world.”

Officials say this stretch of U.S. 101 has a typical traffic volume of 300,000 vehicles each day. A public-private partnership, including agencies like the wildlife federation and the California Department of Transportation, is coming together to build a 200-foot long, 165-foot wide crossing across this section of the road.

Roughly 60% of the funding for the $90 million effort is from private donations, with the rest from public funds earmarked for conservation. The bridge will be named the Wallis Annenberg Wildlife Crossing in honor of one of the biggest contributors.

The efforts of all involved are finally helping bring to reality a project that Pratt has been working on for nearly a decade.

She says, “This is an unprecedented project that Los Angeles should be incredibly proud of. Back then it was just an idea.”


The National Park Service has been studying mountain lions in the area for decades. They say that vehicle strikes are a leading cause of death for the species. Another problem is mountain lions killing each other, which wildlife experts say may be made worse by the freeways and development boxing them in. Finally, inbreeding has been common because the cats can’t spread out around the area. This has led to mountain lions in the Santa Monica Mountains having the lowest levels of genetic diversity ever recorded in the west.

The NPS says the long-term survival of this population will rely upon their ability to move across regions and maintain genetic diversity. Those behind the project are hoping the crossing will help meet these objectives.

The crossing – which will feature native vegetation, irrigation systems, sound walls, and light deflectors to minimize disturbances to wildlife – will also help coyotes, deer, lizards, and other animals traverse the roadway.

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