Saving California Mountain Lions: In-Depth Information

Threatened by Sprawl, Highways, Poison

Humans are the number-one cause of death for California mountain lions.

Lack of connectivity due to decades of extending roads and development into mountain lion habitat, with little regard for the animals’ movement needs, is causing their demise. This has led to high levels of inbreeding and genetic isolation, about 100 car strikes annually throughout the state, and increases in human conflict.

And although hunting mountain lions for sport is no longer legal in California (thanks to Proposition 117), about 100 lions a year are legally killed after being accused of preying on livestock or pets.

Cougars can also die from eating animals that have ingested rat poison, as well as from poaching, disease and human-caused wildfires.

Southern California, Central Coastal Cougars at Risk

Five mountain lion populations in Southern California and along the Central Coast are vulnerable to extinction if connectivity isn’t improved and habitat isn’t protected, according to the California Department of Fish and Wildlife. Mountain lions in the Santa Ana Mountains, Santa Monica Mountains, San Gabriel and San Bernardino Mountains, Santa Cruz Mountains, and Eastern Peninsular Range are at the greatest risk.

Fragmentation and isolation can cause inbreeding and reduced genetic diversity. This can lead to inbreeding depression, which can result in reproductive issues, physical defects, increased susceptibility to disease and, ultimately, population extinction.

The endangered Florida panther shows how inbreeding depression can compromise an entire species. In the 1990s Florida panthers were almost extinct: Fewer than 20–25 individuals remained in the wild. To revive the population, biologists had to relocate Texas pumas to restore Florida panthers’ genetic health.

Like Florida panthers, Southern California mountain lions in the Santa Ana and Santa Monica mountains are extremely isolated by freeways and development.

A recent study has documented high levels of inbreeding and rapidly declining genetic diversity in these populations. Researchers predict that if inbreeding depression occurs, the Santa Ana mountain lions could go extinct within about 12 years and the Santa Monica mountain lions within 15 years.

Other populations in Southern California — including those in the San Gabriel/San Bernardino Mountains and Eastern Peninsular Range — also suffer from habitat fragmentation, low genetic diversity and high levels of human-caused mortalities.

The San Gabriel/San Bernardino mountain lion population represents a key linkage between Northern, Southern and Central Coast mountain lions. Intact habitat in the Tehachapi, Sierra Pelona, San Gabriel and San Bernardino mountains is vital for statewide genetic connectivity and the continued survival of California mountain lions.

Farther north, the Santa Cruz Mountains population suffers from low genetic diversity, with freeways (most notably Highway 17 and Interstate 280) and development blocking lion movement.

Wildlife Crossings — Not More Development and Freeways

Without quick action mountain lions in Southern California and the Central Coast may go extinct. They badly need wildlife crossings over highways to allow them to mix with other populations and maintain genetic diversity.

Although advocates and officials have been working with Caltrans for many years to build crossings, there’s not enough connectivity for mountain lions to survive.

Caltrans lacks a clear legal responsibility to help these mountain lions (and other wildlife), and the agency spends billions of dollars on massive new freeway projects that will fragment lion habitat while needed crossings remain unbuilt.

For example, Caltrans recently approved an $830 million expansion of Highway 138 from two to six lanes in remote wildlands next to the Angeles National Forest. This project will create a major barrier for lions.

Despite the dire situation for Southern California and Central Coast mountain lions, local authorities continue to approve projects in known mountain lion habitat and important linkages. Here are some examples:

  • Los Angeles County supervisors recently approved the 1,300-acre Northlake development, which would constrict a key linkage between the Angeles National Forest and Los Padres National Forest.
  • L.A. County also recently approved the 12,000-acre Centennial development, which would sever a five-mile-wide habitat linkage used by mountain lions. The city of Temecula greenlighted the 270-acre Altair development in the last viable linkage for lions between the Santa Ana Mountains and the Eastern Peninsular Range.

Fighting to Protect California Mountain Lions

The Center is working to secure state-level protection for California mountain lions. In June 2019 we petitioned the California Fish and Game Commission to list the Southern California and Central Coast lion populations as a threatened “evolutionarily significant unit” under the California Endangered Species Act.

That would prevent state and local authorities from approving highway or development projects that jeopardize the persistence of these populations by not accounting for adequate connectivity. And state agencies would have a clear legal mandate to protect mountain lions and improve connectivity, such as by proactively building wildlife crossings at existing barriers and upgrading culverts.

Listing would also grant state wildlife officials greater authority over projects that might harm lions, and they would be able to develop and implement a recovery plan. And listing would likely constrain the issuance of lethal permits that the California Department of Fish and Wildlife would be able to administer for depredation kills.

We’re also pushing for statewide legislation to fund and build wildlife crossings in needed areas to prevent wildlife-vehicle collisions and give mountain lions and other animals room to live.

At the local level, Ventura County adopted a first-of-its-kind ordinance with support from the Center to protect habitat connectivity and wildlife movement corridors for mountain lions and other species.

We continue to fight individual projects that threaten California mountain lions. In January 2018 we led a coalition challenging the Altair development, and the court issued a preliminary ruling in our favor in November 2019. We also filed suits in May 2019 against the Northlake and Centennial developments, which will go to trial in 2020.



Relevant Scientific Studies

Benson, J. F., Mahoney, P. J., Sikich, J. A., Serieys, L. E. K., Pollinger, J. P., Ernest, H. B., & Riley, S. P. D. (2016). Interactions between demography, genetics, and landscape connectivity increase extinction probability for a small population of large carnivores in a major metropolitan area. Proceedings of the Royal Society B: Biological Sciences, 283(1837), 20160957.

Benson, J. F., Mahoney, P. J., Vickers, T. W., Sikich, J. A., Beier, P., Riley, S. P. D., … Boyce, W. M. (2019). Extinction vortex dynamics of top predators isolated by urbanization. Ecological Applications, e01868.

Dellinger, J. A. (2019). Relationship between habitat and genetics in a wide-ranging carnivore. Presented at April 19, 2019 Inter- gency Working Group Meeting in Temecula, CA.

Ernest, H. B., Vickers, T. W., Morrison, S. A., Buchalski, M. R., & Boyce, W. M. (2014). Fractured genetic connectivity threatens a Southern California puma (Puma concolor) population. PLoS ONE, 9(10).

Gustafson, K. D., Gagne, R. B., Vickers, T. W., Riley, S. P. D., Wilmers, C. C., Bleich, V. C., … Ernest, H. B. (2018). Genetic source–sink dynamics among naturally structured and anthropogenically fragmented puma populations. Conservation Genetics, 20(2), 215-227.

Riley, S. P. D., Serieys, L. E. K., Pollinger, J. P., Sikich, J. A., Dalbeck, L., Wayne, R. K., & Ernest, H. B. (2014). Individual behaviors dominate the dynamics of an urban mountain lion population isolated by roads. Current Biology, 24(17), 1989–1994.

Vickers, T. W., Sanchez, J. N., Johnson, C. K., Morrison, S. A., Botta, R., Smith, T., … Boyce, W. M. (2015). Survival and mortality of pumas (Puma concolor) in a fragmented, urbanizing landscape. PLoS ONE, 10(7), 1–18.

Mountain lion cub photo courtesy National Park Service