Mega-Freeways and Mountain Lions
As human populations readily expand, the need to invest heavily into solutions to prevent mountain lion (Puma concolor) extinction in the Santa Monica mountains only compounds. Inbreeding, vehicle-related mortality, and human-related conflicts have only become exasperated as traditional mountain lion ranges have been limited by rapid urbanization. To combat these issues, particularly with cougar-vehicle collisions, the improvement of habitat corridors has been suggested to increase genetic diversity throughout fragmented landscapes. In hopes of implementing wildlife crossings across the state of California’s mega freeways, the loss of such beautiful creatures could be halted in its tracts.
For many, Highway 101—one of California’s mega-freeways—is a means to travel. From friends to romantic partners’ homes, to workplaces or to In-and-Out and beyond, roads connect us from point A to point B. For many mountain lions located in the Santa Monica mountains, however, face a different problem. If freeways for us are rapid expanses to get us quickly to where we need to be, then freeways for mountain lions are equivalent to brick walls. Los Angeles, California is only one of two metropolises that house mountain lions within their borders, yet their presence is continually threatened by the mega-freeways that characterize the state (National Park Service n.d.).
Lack of genetic diversity due to the immense fragmentation of the land, is a significant risk for these cougars. Inbreeding among relatives is feared in this population, due to the inability to maneuver across the landscape to find suitable mates (Benson, et al. 2016) Without ideal mating partners, the chance of inbreeding depression is likely. In fact, the genetic variability in mountain lions located in the Santa Monica mountains are “among the lowest ever documented for the species” (National Park Service n.d.). With estimates as high as 99.7% for extinctions of these populations, there must be mitigation to improve habitat connectivity between urban and rural ranges (Benson, et al. 2016).
How can we fix such extreme disparities, then? Perhaps the answer isn’t as difficult as it might seem. Although a fairly new wildlife management technique, motions to construct wildlife crossings has made significant headway in recent years. These crossings serve to minimize space and danger while traveling between fragmented populations. As of 2023, a project to construct the largest crossing in the world hopes to be unveiled (SaveLAcougars n.d.). Where better to place this project than at the lowest point of genetic diversity for cougars? Across 10 lanes of freeway traffic, highway 101 will bear the honor.
Though inspiring and necessary to the long-lasting benefit of California mountain lions, this project is not without its costs. A significant one is the price. $87 million sits on the trophy of largest wildlife crossing in the world—a mighty but hefty ask (The Guardian). However steep, it’s important to note that this crossing not only benefits the inbreeding mountain lions, but many different species. Those that have also been cut off by massive freeways like highway 101 can use the space, just as freely as mountain lions do.
Overall, it’s not only important to prioritize wildlife crossings for genetically poor mountain lions, but also for ourselves. If vehicle-related mortality for cougars is one of the leading causes of death in Los Angeles, then we must remember that property damage, insurance, and human health also becomes a risk (National Park Service n.d.). Additionally, as mountain lions expand back into more appropriate ranges, human conflicts in general could be scattered across more rural spaces, occupying “critical open space to the north in like the Simi Hills, Santa Susana Mountains, the over 2,700 square miles of Los Padres National Forest, and many more thousands of square miles of habitat beyond” (SaveLACougars n.d.). As this habitat range is amplified, the more cougars can minimize their direct impact.
The fight to keep Santa Monica Mountain lions from extinction may be a continuous battle. However, enabled with tools like wildlife crossings, we can reinstate some ecological balance in the range of one of California’s favorite predators. This is not without cost nor hardship, but the battle to protect wildlife is one that should not be overlooked. Genetic diversity must be improved if we want to sustain these animals on the landscape. We at least owe them that. We did, after all, build a nearly 4-million-person metropolis right on their sacred breeding grounds.
Sources
Benson, John F., et al. “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, 31 Aug. 2016, https://royalsocietypublishing.org/doi/10.1098/rspb.2016.0957.
“Los Angeles to Build World's Largest Wildlife Bridge across 10-Lane Freeway.” The Guardian, Guardian News and Media, 21 Aug. 2019, https://www.theguardian.com/environment/2019/aug/21/los-angeles-wildlife-bridge-mountain-lions.
“Mountain Lions Face Loss of Genetic Diversity (U.S. National Park Service).” National Park Service. U.S. Department of the Interior. https://www.nps.gov/articles/mountain-lions-face-loss-of-genetic-diversity.htm.
Save LA Cougars, 29 Nov. 2021, https://savelacougars.org/wp-content/uploads/2019/10/SaveLACougars-Overview-2019- Final.pdf
