The Truth about Mountain Lions

By James Hale;                                                                                           

Mountain lion in a vineyard
Mountain lion in a vineyard

Mountain lion ancestors originated in North America around 10 million years ago from the ancestral stock of Saber-toothed Cats (Smilodon fatalis) and Scimitar Cat (Homotherium serum) which originated around 25 million years ago. The Saber-toothed cats lived between 2.5 million years ago to 10,000 years ago. The mountain lion lineage branched off around 1 million years ago. The two species of saber tooth cats, as well as the North American Cheetah (Miracinonyx trumani)and the North American Lion (Panthera atrox) were extirpated in North America around 10,000 years ago, starting with the Younger Dryas Cold Spell or Big Freeze (12,800 – 11,500 Before Present) during the end of the Pleistocene Epoch (2,588,000 – 11,700 million years ago). Climate change at the end of the Pleistocene and perhaps overexploitation by the PaleoIndians led to the extinction of the Megafauna. Mountain lion populations flourished thereafter.


Mountain lions (Puma concolor) are presently the only large, obligate carnivore thriving in self-sustaining populations across western North America. The species has existed here along with its major prey – Mule Deer ( Odocoileus hemionus), White-tailed Deer (Odocoileus virginianus), Elk (Cervus elaphus), Moose (Alces alces), and Bighorn Sheep (Ovis canadensis) – for at least 13,000 years. Ecologically, mountain lions strongly influence energy flow in ecosystems, are a potent selective force on prey animals, modulate prey population dynamics, indirectly affect herbivory in plant communities, influence competitive interactions between herbivores, and compete with other carnivores for prey. Moreover, because self-sustaining mountain lion populations require expansive, interconnected wild land, conservation strategies designed to benefit mountain lions also benefit an array of other wildlife.

Unregulated mountain lion hunting and habitat alterations that affected prey numbers, caused the near extinction of the mountain lion in eastern North America. By 1900, mountain lions had largely been extirpated east of the Rocky Mountains, with the exception of Florida. Through the first half of the 20th century, management emphasized preemptive eradication. Bounties were paid as an incentive to remove mountain lions for protection of wild ungulates and domestic livestock. The payments were significant for the time. In the 1920’s, California paid bounties of $30 for a female mountain lion and $20 for a male.

Bounties continued to be paid throughout the western states into the 1960’s, when mountain lion management shifted to a brief non-bountied but non-protected status. Coincident with the abolishment of bounties, depredation policies became less preemptive and more reactive, targeting mountain lions associated with livestock losses. By the early 1970’s, mountain lions were managed as a game species across most states and provinces. This represented the first form of protection for mountain lion populations. An average of 156 special, depredation permits were issued annually in California from 2005 to 2009, with an average of 73 mountain lions killed each year during this period. On June 5, 1990, the voters of California approved Proposition 117, the California Wildlife Protection Act, prohibiting the sport hunting of the California Mountain Lion, where they remain a “specially protected species”, and requiring California to spend no less than $30 million a year on wildlife habitat protection and related purposes. Today, an estimated 4,000 to 5,000 mountain lions inhabit California.

Management of mountain lions is difficult for several reasons: they are secretive, they exist at low population densities, they impact wild and domestic prey, they can threaten human safety, and public attitudes about them differ widely. Although mountain lions are widely distributed in western North America and are not endangered, landscapes and human attitudes are changing rapidly and bringing new management challenges. In California, the statewide deer population has dropped from 2 million in the 1960’s to about 445,000, according to the CDFW. For decades, the state’s population growth has converted over 75,000 acres of wildlife habitat per year to housing. Logging, agriculture, and other practices have dramatically reduced or altered habitat. Next to humans, the mountain lion is the chief predator of deer, with individuals taking about 50 deer annually, which increases the desire of some hunters to eliminate their competition. In National Parks and other areas where deer are not hunted, mountain lions are a necessary control on deer populations, and their presence should be encouraged. Mountain lions do not exterminate deer. The predator-prey relationship of mountain lions and deer was in balance for millennia, long before humans were present or began management programs.

I suggest there are three separate subpopulations of the Contra Costa County metapopulation of mountain lions. They are isolated, disjunct populations where Highways 680, 580, 80, and 24 present ecological barriers to mountain lion dispersal, thereby threatening their existence. I’ve named them the Briones, Las Trampas, and Diablo populations. At present, it is unknown if these subpopulations are source populations, where mean growth rate is positive, or sink populations, where mean growth rate is negative. Anecdotal data suggests they are still source populations. Empirical data from research will provide much needed information on their population dynamics. In the absence of immigration of new individuals into a subpopulation, hybrid vigor and genetic diversity are lost, and the population eventually collapses due to inbreeding, disease, and other factors. Dispersing mountain lions are forced to navigate across these ecological barriers such as freeways, suburbanization, and other obstacles to their movements. The identification, preservation, conservation, and management of the critical habitat linkages are becoming increasingly more important if mountain lions are to remain an integral component of our landscape. Currently I and other researchers have remote infrared, motion detection trail cameras deployed in the East Bay. We hope to initiate a satellite biotelemetry study soon which will provide much needed data on east bay mountain lion population dynamics.

As available habitat diminishes and mountain lion populations reach the carrying capacity, human – mountain lion interactions continue to increase. Such was the case in Cupertino recently when a mountain lion attacked a young boy. Mountain lions which show aggressive behavior or attack humans are euthanized. Senate Bill 132 requires the California Department of Fish and Wildlife to utilize nonlethal options when responding to mountain lion incidents that don’t pose an immediate risk to humans. Most of these encounters involve starving or dispersing subadult mountain lions in search of their own territories. Here are some compelling facts. Since 1890, in California, there have been only 6 deaths and 17 confirmed attacks by mountain lions on humans. Deer have injured over 500,000 humans and killed over 3,000 nationally in the past 100 years. One has a 1,000X greater chance being struck by lightning and 500X greater chance of being attacked and killed by a domestic dog or deer, than encountering a mountain lion. Humans have a 1 in 775 million chance of making contact with a mountain lion in the western United States, and 1 in 3.4 billion for the entire country. In South Dakota, humans have a 1 in 65 chance of colliding with a deer in your automobile. I have been blessed with nearly 20 chance encounters with mountain lions in my field experience and never was threatened with aggressive behavior. We need to continue to support our local conservation organizations such as the East Bay Regional Parks District, Mount Diablo State Park, EBMUD, CCWD, Save Mount Diablo, Muir Heritage Land Trust, Felidae Conservation Fund, California Mountain Lion Foundation, and our open spaces, which provide much needed habitat.



James M. Hale is a wildlife biologist and Vice Chair of the Contra Costa Fish and Wildlife Committee.