The California Department of Transportation has scheduled groundbreaking for early 2022 on one such crossing, a wildlife bridge over Highway 101 in Agoura Hills in northwestern Los Angeles County, thanks to a mix of public and private funding. Biologists and land managers hope this project will lead to more crossings. In fact, early plans are being formulated for a possible structure over Interstate 15 in in Riverside County.

Crossings, the researchers say, help all local animal species amp up their genetic mix and, when feasible, are preferable to the Florida scheme of transporting mountain lions into circumscribed local habitats, which is not a long-term solution and can often result in mortality for translocated animals.

For now, the researchers will continue monitoring how the newly discovered fertility issues affect the mountain lions’ breeding, keeping a close eye on potential decreases in the number of kitten litters and kitten survival rates.

“If we don’t do anything to add genetic diversity, the end is near,” Huffmeyer stressed. “That sounds dramatic, but that’s what we’ve seen.”

Also contributing to the research were senior author Robert Wayne, a UCLA distinguished professor of ecology and evolutionary biology; Winston Vickers, director of the Mountain Lion Project at the UC Davis Wildlife Health Center; and NPS field biologist Jeff Sikich.