The biggest threat to Southern California mountain lions is us, confirms a comprehensive 13-year study of the population's mortality and survival from the University of California, Davis.
The study, published in the journal PLOS ONE, combined genetic and demographic data to determine that even though hunting mountain lions is prohibited in California, humans caused more than half the known deaths of mountain lions studied. Most were killed through vehicle collisions, depredation permits, illegal shootings, public-safety removals or human-caused wildfire. Annual survival rates were only about 56 percent.
Exacerbating the problem is an interstate highway, I-15, a major thoroughfare connecting San Bernardino, Riverside and San Diego counties that has proven nearly impossible for the mountain lions to cross. It bisects the study area, which stretches from Orange County, south to the Mexican border and east to the Salton Sea. Crossing the interstate, especially for the animals of breeding age, is important for this population's declining genetic diversity -- and long-term health and survival.
