Why the recent capture of mountain lion P-129 is a big deal for the 101 Freeway wildlife crossing

The Wallis Annenberg Wildlife Crossing in Agoura Hills isn’t slated to open until Fall 2026, but there’s already been a wild discovery near the forested overpass.

National Park Service biologists recently captured and collared a female mountain lion, now named P-129, inside the construction site of the forthcoming crossing.

She is the third mountain lion to be captured through the crossing site, and the first since construction started.

Anaerial view of the Wildlife Crossing site in progress taken on December 6, 2025.

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Beth Pratt

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“The mountain lion was captured and tracked and traveling right around the Wallis Annenberg Wildlife Crossing — right inside of it,” said Beth Pratt, Regional Executive Director of the National Wildlife Federation, one of the organizations that's managing construction of the project.

“To actually capture one right in the site of the crossing being built was pretty special,” she added.

A Puma’s path

P-129 was captured as part of the National Park Services’ Puma research project.

Scientists with the service have been studying mountain lions in the Santa Monica Mountains and surrounding region since 2002. It’s one of the longest continuous urban mountain lion studies.

“The knowledge that the Park Service has gleaned from these decades of research have helped us understand how they travel and use the landscape in the Santa Monica Mountains,” Pratt told LAist.

The soon-to-be completed wildlife crossing that will go over the 101 freeway was set in motion because of research done by the Puma project.

Although the crossing is intended for all wildlife, mountain lions are the ones most at risk from isolation caused by the freeway, said Pratt. The discovery of genetic degradation among mountain lions is what raised alarm bells that prompted the construction of the overpass.

In 2020, birth defects began manifesting in tracking data. Kink tails, only one descended testis, and the degradation of sperm quality all pointed to the next inevitable development: sterility.

Indeed, Pratt said a major goal of the crossing is to bring "dates" — mating partners — for these mountain lions who are living in the Santa Monica mountains.

Coming next Fall

Construction workers for the Wallis Annenberg Wildlife Crossing continue work on the project.

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Caltrans

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Beth Pratt

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The crossing has been under construction since 2022 and is on track to open next Fall. The main structure over the 101 has been completed, with a habitat of native plants growing on top.

Right now, Pratt said underway is a massive utility relocation of electricity, water, and gas lines.

“We have to move those utility lines out of the way, and then the secondary structure over Agoura Road is being constructed as well,” she said.

With the big unveiling in sight, the team is now taking bets on which animal will make its maiden passage next year.

“It could be [P-129], or it could be the dominant male in the area," Pratt said. "Or it could be a new cat that we don’t even know.”