Author: Paige Munson

Recent tragedies such as the mountain lion that attacked and killed Taylen Brooks in California and the harrowing mountain lion attack on Keri Bergere and her friends while mountain biking in Washington have left the rare occurrence of mountain lion attacks fresh in the minds of many.  

The Mountain Lion Foundation offers our sincere condolences to those who have been affected by these attacks. On the rare occasions when they do happen, mountain lion attacks can be devastating.  

Mountain lion attacks are incredibly rare, but there is no such thing as “risk free”  

In spite of their rarity, each story of a mountain lion attack can incite fear, often quickly followed by a flurry of ill-informed plans to prevent such attacks. There have been 29 cases (not all confirmed) of fatal mountain lion attacks on humans in North America since 1868, for an average of about 0.18 attacks per year. For context, each year in the US on average 777 people die from mosquito-borne illnesses, 28 people are struck by lightning, at least 20 people die from firearm-related hunting accidents, 86 people die from animal venom, and about 35,000 to 45,000 people die from motor vehicle accidents. By contrast, in California alone, two mountain lions die of car strikes every week, on average. 

Mountain lions are not a major public safety risk, but attacks on humans may have become more frequent after bounties were abolished and lion populations began to recover in the early 20th century. Despite the long odds of human injury, hearing about an attack can make people want to “do something.” However, it’s important to keep these risks in perspective: wildlife, including mountain lions, are valuable to people for both aesthetic and ecological reasons. We value activities that bring us into the outdoors, closer to our wild neighbors. As we work, play, and recreate in these wild spaces, our risks will never truly be eliminated. There is no such thing as “risk free” in the wilderness.  

In his 1992 paper on the topic, Paul Beier stated: 

“Although attacks were much rarer in the “bad old days” when deer were market hunted and cougars were shot on sight. The risk was still greater than zero. There has been at least 1 attack in every decade since 1890. It is impossible to reduce this small risk to zero without eliminating either cougars or humans from cougar habitat. Neither ‘solution’ is acceptable.”  

The research on mountain lion attacks in North America 

With an incredibly small sample size and varying record-keeping practices for different incidents, understanding the risk factors when analyzing mountain lion attacks has been a challenge for many in the field. Nonetheless, researchers have studied these attacks to understand them better.  

Most attacks from mountain lions happen during the day, in summer and fall, and in wildlife areas where humans are recreating. The attacks typically do not happen when mountain lions are most active, nor are lions coming into developed spaces to attack humans. The attacks occur when humans are most active in mountain lion territories, indicating mountain lions are not seeking people out.  

Mattson et al (2011) created a model using data from all mountain lion attacks in North America since 1890, to identify risks factors:  

Young and/or unhealthy mountain lions are the most likely to attack humans, and the least likely to cause death in the victim. However, in the incredibly rare instances where healthy adult mountain lions attack people, the attack is more likely to be fatal — while the risks of adult attacks are lower, the consequences are greater.  

The presence of a dog seems to reduce the likelihood of a mountain lion attack during the daylight. Dogs do not need to be excluded from trails to prevent attacks. This doesn’t hold true when a dog is at a residence at night. Securing dogs inside at night is a safer choice for the dog. (House cats too, for that matter.)  

When encountering a mountain lion, the people who are aggressive (yelling, throwing objects, looming large, charging the animal, or using a weapon) are much more likely to avoid an attack entirely.   

Children are more likely to be attacked by mountain lions than adults, but the presence of adults in a group doesn’t seem to deter a mountain lion from attacking. However, the presence of adults able to defend the child dramatically increases a child’s chance of survival if attacked.  

Activity also seemed to affect the likelihood of an attack and fatality. People engaged in more erratic or high-energy activities, like running or mountain biking, were at a greater risk for attack and fatality. This may be because the prey response is more easily triggered in mountain lions from these movements. Additionally, these activities may reduce a person’s ability to respond quickly to a mountain lion and act aggressively, or to notice a nearby mountain lion quickly enough to stop and back away.  

Compared to other large carnivores, mountain lion attacks have had a low fatality rate. Of known attacks, 15% of mountain lion attacks were fatal. Known attacks from the African lions, tigers, and leopards were all much deadlier with fatality rates of 62%, 78%, and 32%, respectively. 

Management approaches to reduce attacks 

Most people agree that preserving public safety is a priority. Mountain lion encounters are unlikely, and the likelihood of death from one is even slimmer, making their public safety risk very low. Regardless, we should still do what we can to prevent attacks.  

Research into mountain lion management has identified that high levels of hunting lead to a population made up of primarily young mountain lions. This leads researchers such as Beier (1991) and Mattson, et al (2011) to speculate that higher hunting levels could make mountain lion populations “riskier.” The ability to reduce attacks through reduced hunting levels has never been observed, however we do have data to show that the absence of hunting doesn’t make an attack any more likely. In fact, some of the regions with the highest level of fatality due to mountain lion attacks also have some of the highest levels of hunting, such as Vancouver Island. Research on livestock depredations shows the same pattern, with areas with high hunting or more frequent lethal responses to depredation (including El Dorado County, CA, according to research by Dellinger, et al., 2021) showing higher rates of conflict in subsequent years. 

In states where mountain lions are hunted, advocating for low levels of hunting that do not result in populations with age structures skewed toward young cats could be a strategy to reduce the likelihood of mountain lion attacks.  

Staying safe and enjoying the outdoors 

The best way to avoid a mountain lion attack is to never go into wild lands with mountain lions. For most people who love the outdoors, though, that is an unacceptable way to live, especially to avoid such a low-likelihood event. You are almost certain to never be faced with a mountain lion attack and are most likely safe to spend your time enjoying the outdoors.  

To stay safe in mountain lion country you can carry pepper spray or a loud safety horn, travel in a group, supervise children, stay vigilant, and maybe bring a dog. Learn more about mountain lion safety here.  

It is the Mountain Lion Foundation’s hope that attacks on humans are as rare as possible, and that people can continue to safely enjoy the outdoors and share the land with wildlife.  

 

 

References 

Beier, P. (1992). Cougar attacks on humans: an update and some further reflections. In Proceedings of the Vertebrate Pest Conference (Vol. 15, No. 15). 

Brothers tried to fight off mountain lion during fatal attack in Northern California, family says. (2024). Associated Press. https://apnews.com/article/california-mountain-lion-attack-brothers-92b8b951c5e8d62a889af494d2d3642d 

Dellinger, J. A., Macon, D. K., Rudd, J. L., Clifford, D. L., & Torres, S. G. (2021). Temporal trends and drivers of mountain lion depredation in California, USA. Human Wildlife Interactions, 15(1). https://doi.org/https://doi.org/10.26077/c5bb-de20

Grant, Melissa. (2024) Five against the wild: A gripping tale of courage and survival in cougar territory. Living Snoqualmie. https://livingsnoqualmie.com/five-against-the-wild-a-gripping-tale-of-courage-and-survival-in-cougar-territory/ 

Mattson, D., Logan, K., & Sweanor, L. (2011). Factors governing risk of cougar attacks on humans. Human-Wildlife Interactions, 5(1), 135–158. https://www.jstor.org/stable/24868869 

Laundré, J. W., & Papouchis, C. (2020). The Elephant in the room: What can we learn from California regarding the use of sport hunting of pumas (Puma concolor) as a management tool?. PLOS ONE, 15(2), e0224638. 

Peebles, K. A., Wielgus, R. B., Maletzke, B. T., & Swanson, M. E. (2013). Effects of remedial sport hunting on cougar complaints and livestock depredations. PLOS ONE, 8(11), e79713. 

Robinson, H., & DeSimone, R. (2011). The Garnet Range mountain lion study: characteristics of a hunted population in west-central Montana. Montana Department of Fish, Wildlife & Parks. 

Wang YY, Weiser TG, Forrester JD. Cougar (Puma concolor) Injury in the United States. Wilderness & Environmental Medicine. 2019;30(3):244-250. doi:10.1016/j.wem.2019.04.002 

The US Fish and Wildlife Service (USFWS) released a policy update for public comment through March 5th, 2024, for the National Wildlife Refuge System (NWRS). The purpose behind these regulations is to provide clarification and directives for ensuring biological integrity, diversity, and ecological health (BIDEH). The policy update also explicitly addresses climate change.  

What might the changes mean for mountain lions and other wildlife in the Wildlife Refuge System? 

The National Wildlife Refuge System (NWRS)

Size and Benefits of the NWRS

The National Wildlife Refuge System is one of the many public land types managed under the US Department of the Interior. The National Wildlife Refuge system encompasses 760 million marine acres and 95 million land acres. The amount of land acres it protects is equivalent to nearly 15,000 square miles, comparable to the state of Maryland.  

The Wildlife Refuge System comprises 15 percent of the 620 million acres of federally owned land in the United States. Federally owned land makes up approximately 27 percent of the United States, most of which is in the West. Despite the “smallness” of our 95-million-acre National Wildlife Refuge System, the benefits to wildlife and communities are immense.

A 2022 study assessed the social cost of carbon and estimated the carbon sequestration of the National Wildlife Refuge system results in about 976 million dollars in avoided emissions due to the Refuge System’s conservation practices.  Maintaining protected lands such as the National Wildlife Refuge System is one of the many necessary actions to fight climate change.   

BIDEH in the National Wildlife Refuge System  

The National Wildlife Refuge System is mandated to uphold BIDEH: biological integrity, diversity, and ecological health). To clarify and strengthen the BIDEH mandate, the Service provided the following definitions in their proposed updates: 

Biological integrity: the capacity of an ecological system to support and maintain a full range of biotic composition, structure, function and processes over time that exhibit diversity, connectivity, and resilience at genetic, organism, population, and community levels.  

Diversity: the richness and abundance of living organisms, the genetic differences among them, and communities and ecosystems in which they occur.   

Ecological health: composition structure and functioning of soil, water, air, and other abiotic features, including the abiotic processes that shape the environment. 

Before these updates, BIDEH was evaluated by referencing historical conditions. With the updates, BIDEH will also consider irreversible landscape changes from climate change and human activity.  

Changes in the proposed policy updates

The updated regulations specifically prohibit the use of carnivore control, agricultural use, and mosquito control on Wildlife Refuges. We support these changes and also believe more can be done.

Carnivore control  

There is little evidence to support the use of killing native carnivores as a management tool. Increasing evidence each year points to the profound benefits of carnivores in their ecosystems. Yet, carnivore, or predator control, is still widely practiced in the US and sanctioned through state wildlife agencies, even the USDA. Much of this is in part due to long-standing beliefs toward wild carnivores, financial interests, and the US history of persecuting America’s wildlife to the point of mass extirpation and extinction.   

This prohibition on carnivore control will help ensure the protection of important keystone species on Wildlife Refuges. However, the language isn’t absolute: “We may implement lethal predator control only when all other feasible methods have been fully evaluated and such control is considered the only practical means of addressing a specific, significant conservation concern and ensuring BIDEH.”   

Current use of carnivore control in the Hart Mountain National Antelope Refuge

As hopeful as these changes are, we may still see the use of lethal control for carnivores including mountain lions. One example of lethal control of mountain lions has been in the Hart Mountain National Antelope Refuge (NAR) in Oregon because of a decline in the bighorn sheep population.   

Bighorn sheep were extirpated in Oregon, but the Hart Mountain population was established through conservation translocations of 20 sheep in 1954. The herd was incredibly successful, and even became a source population for other efforts to establish bighorn sheep herds in Oregon. In 2017, the population reached 150 individuals before it began declining, with no sign of disease. In 2020 the population was down to 48 individuals.

Researchers assessed that habitat was a likely cause, but current rates of mortality and decline were imperiling the population. Most of this mortality came from mountain lion predation. Typically, ungulates are resilient to predation, but small populations, those lacking in quality habitat, or those experiencing types of human disturbance can become more vulnerable to any form of mortality, including predation.   

To help the bighorn sheep population, habitat restoration efforts and the lethal control of mountain lions began on the refuge in 2022 according to USFWS’s approved management plan. It is unclear if lethal control of mountain lions will continue in the Hart Mountain NAR, given the policy updates. We expect that it likely will.   

The need for nonlethal carnivore control strategies in endangered species protection

Wildlife translocations and lethal predator control are management interventions that have been used on behalf of bighorn sheep for decades; however, nonlethal approaches have not been. Nonlethal approaches to prevent predation are specific to predator species, prey species, and existing habitat. Due to most prey populations’ resilience to predation from native carnivores, there has been little occasion to explore nonlethal methods to prevent predation on bighorn sheep.   

In cases where immediate interventions are required, managers rely on the most supported and easiest to implement solution. From this standpoint, lethal removal of mountain lions is the favored solution as it is supported by current evidence specifically for struggling bighorn sheep populations. However, this also will not allow for the advancement of nonlethal methods for protecting vulnerable bighorn sheep populations from mortality.  

Under the proposed policy updates, it is likely that nonlethal methods simply won’t be used or tested because they aren’t well explored yet and thus aren’t supported by enough data. The Mountain Lion Foundation has recommended that the USFWS amend the language to require that when lethal control is used, nonlethal methods must be utilized and tested at the same time. If the USFWS accepts these changes, it could help expand the use of nonlethal strategies and our knowledge base for achieving conservation objectives without killing native carnivores.   

Additionally, lethal control of carnivores may become too much of a threat to endangered carnivores. The mountain lion is currently under review for state endangered species status in California, and conservation is best served with approaches that do not rely on choosing which endangered species to kill.  

Submit your comments

The Mountain Lion Foundation applauds the policy updates proposed by USFWS for the National Wildlife Refuge Service as an important step in safeguarding the Refuge system. There are further steps that could be taken, specifically regarding their language on carnivore control, but we encourage the public to support the most recent proposal.

USFWS has received more than 20,000 comments so far. Submit your comments on the proposed rule updates here through March 5.  

You’ve probably seen some recent media coverage about the “lower than previously thought” number of mountain lions in California. These preliminary estimates, released by the California Mountain Lion Project, are just that — preliminary. Here at the Mountain Lion Foundation, part of our work is to be a clearinghouse for the most accurate and up to date scientific information on mountain lions. With that in mind, we reached out to some of the scientists at the California Mountain Lion Project, now known as California Carnivores, to ask, “What’s the story with these new, lower estimates of the number of lions in California?” 

What is the California Mountain Lion Project?  

The California Mountain Lion Project formed in 2001 under the Karen C. Drayer Wildlife Health Center at the University of California at Davis. Originally, the project centered on the Southern California mountain lion population, a major conservation concern. The project’s research  focused on habitat fragmentation, disease, prey interactions with mountain lions, and coexistence with humans in Southern California. The program has expanded over the years, and its name changed to California Carnivores to reflect that.  

How many mountain lions are there in California?  

Justin Dellinger and the rest of the research team’s work has resulted in two preliminary population estimates for mountain lions of all age classes (adult mountain lions, juveniles, and kittens) in California. Both estimates represent the median value of two population estimate ranges utilizing slightly different data, including telemetry data from GPS collars and genetic sampling. Using only genetic sampling data yielded an estimate of 3,200 mountain lions of all age classes. The method that factored in telemetry data as well yielded an estimate of 4,500 mountain lions of all age classes. 

The estimate of 4,500 mountain lions of all age classes is likely to be the more accurate estimate, as it considered home range sizes of collared animals. Despite the widespread media coverage, these estimates should be considered preliminary until they go through rigorous review by scientific peers.  Also, they cannot be widely used for management until the findings are peer reviewed.  

The old estimate for mountain lions was 6,000. Why is this new number so different?  

The number of 6,000 mountain lions in California was a “back of the napkin” estimate. It took a reasonable mountain lion density and multiplied it by about how much habitat was in the state. This type of calculation has value, especially when there is no robust population assessment. However, the 6,000 mountain lions estimate was always  a weak one.  

The preliminary finding of 4,500 mountain lions was derived from robust data. If it is accepted in peer review, it will likely be the most accurate, current assessment of the mountain lion population in California.  

Ultimately these numbers cannot be compared well, as they came from two different points in time with entirely different methodology. If the population estimate is accepted in peer review, the Mountain Lion Foundation will accept it as the updated number of mountain lions.  

What does this estimate tell us?  

Of course, the preliminary result tells us there are 4,500 mountain lions of all age classes. Even though that number is lower than previously thought, it’s still good news. On a statewide demographic level, mountain lions are doing well in California overall. However, the number of mountain lions in an area is not the only indication of how well mountain lions are doing.  

Genetic health is a major indicator of population health, and often functions as a “canary in the coal mine” for population decline. It is widely understood that habitat fragmentation and lack of connectivity have caused genetic declines in Southern California mountain lion populations, threatening their long-term viability. This threat  prompted the development of the Wallis Annenberg Wildlife Crossing near Los Angeles, along with a number of other important wildlife crossings across the state, and the petition by the Mountain Lion Foundation and the Center for Biological Diversity to list these lions populations as endangered in California. (That petition is currently still under review.)  

However, we can look at this population estimate as a sign of hope. While mountain lions in California are struggling with habitat fragmentation and loss of genetic diversity in some regions, the issues haven’t caused the populations to become too small yet. Having a large enough population size means that populations will be better able to respond to interventions to promote genetic diversity, such as wildlife crossings.  

Mountain lion densities are higher or lower based on the landscape  

Mountain lion density tells us approximately how many mountain lions there are in an area. Typically this is listed in research as “mountain lions per 100 km².” Lion density itself is continuous over the landscape, meaning there won’t be a big jump in lion density in adjacent areas.  

The primary factor that limits how many mountain lions can be in an area, is the availability of prey. Meanwhile, the prey are limited by their access to vegetation for foraging. So, the greatest factor that influences mountain lion densities is typically the vegetation in the area. If there is abundant water and forage for prey species, there will likely be higher mountain lion densities.  

This relationship leads to higher mountain lion densities in regions that have abundant water and forage, like the western Sierra Nevada and the western Coastal Range.  

There are mountain lions in the Central Valley and the Mojave 

There has been some media coverage stating that the Central Valley and Mojave have no mountain lions at all. To clarify, those two regions were not sampled directly so their estimated mountain lion populations were estimated based on other data from the study and the habitat in the area. 

Researcher Justin Dellinger has published works on these populations that can be found here.

Is the mountain lion population increasing or decreasing?  

This preliminary estimate of 4,500 mountain lions of all age classes represents a point in time. Monitoring with similar methods will need to be repeated in the future to assess population trends for mountain lions in California.  

From a number’s perspective alone, mountain lions are doing well. While lion populations in certain areas are lower and more fragile than others, from a statewide perspective, their numbers are not too low. Additionally, mountain lions in California are not overpopulated. Overpopulation was a major fear and fueled opposition to the work of mountain lion advocates on Proposition 117,  which permanently banned mountain lion sport hunting in 1990 in California. Prior to the legislation mountain lion hunting had been on moratorium since 1972. (These efforts during the 1980s eventually gave birth to the Mountain Lion Foundation as a nonprofit organization, in 1986.) Research overwhelmingly shows that mountain lions do not need to be hunted to avoid overpopulation, as their social structures and food availability do that on their own. This research provides another reference point, too: More than 50 years after a ban on hunting, mountain lions have not become overpopulated. 

How does this estimate compare to other states and their methods? 

Most states with mountain lions attempt to estimate their population in some way. Not all of these methods are created equal, however. Some rely heavily on hunter harvest statistics, which introduce considerable bias, and on little to no supplemental field data. Other methods are quite thorough, and data from the field are gathered regularly. The work done by the California Mountain Lion Project stands apart from many of these monitoring efforts mainly by its scope. Studies often intensively study one or two areas and apply those results to the remainder of the state. The new California estimates, by contrast, are sampled from many regions across California. This wide sampling effort will help to achieve a more accurate picture of the mountain lion population.  

Some states have no official estimates at all. Currently, the only states with breeding populations and no official population estimates are Wyoming, Idaho, and Texas. As a result, scientists and managers are largely left to rely on these “back of the napkin” population estimates much like California’s old “6,000 mountain lions in the state” number. By looking at the discrepancy between California’s back of the napkin calculation, and the preliminary study estimate, we see the potential of overestimating populations when real data are not available. This discrepancy has particularly  negative effects when hunting quotas are based on those flawed methods and assumptions.  

Here at the Mountain Lion Foundation, we look forward to seeing this work once it is ready for publication, and we will continue to use the best available evidence in our work to advocate for mountain lions in California and across the country.