Mountain Lion Attacks On People in the U.S. and Canada

Table of Contents

Summary
General Advice About Lion Encounters
Statistics of Attacks
List of Mountain Lion Attacks
Bibliography on Mountain Lions
Source Abbreviations


Summary

This page links to a complete list of mountain lion attacks on people in California, and another complete list of all such attacks in the U.S. If you know of an attack not listed here, please email me for attacks in California, or my coauthor Linda Lewis for attacks outside of California.

I define an attack as one that involves physical contact by mountain lions on people. This does not include an encounter, where a mountain lion may threaten a person, but does not result in physical contact. Nor does it include a sighting, which usually involves no threatening action by the cougar.

Mountain lions are known by many names: cougar, panther, and puma. The "lion" term is due only to their color; in fact cougars are more closely related to leopards than to lions. In the text below, lion will always refer to cougar.

Mountain lion attacks on people apparently increased dramatically since 1986. For example, in California, there were two fatal attacks in 1890 and 1909, and then no further attacks for 77 years, until 1986. From 1986 through 1995, nine verified attacks occurred, an average rate of almost one per year. Attacks were numerous enough to form a support group for attack victims, called California Lion Awareness (CLAW; Outside, 10/95).

Mountain lion sightings have increased dramatically as well, from 59 in 1991 to over 300 in 1994 in California. However, because of a number of reasons, perhaps 80% of all lion sightings are actually deer, bobcats, dogs, and even domestic cats. Part of any increase in sightings is also surely due to the heightened awareness of lions with the increase in attacks. Of course, this means 20% of all mountain lion sightings are of actual mountain lions!

There are a number of possible reasons for the high false rate of "mountain lions" sightings. First, they are camouflage experts, and often one doesn't get to see the entire lion. Second, if you think you are seeing a mountain lion, your adrenaline is undoubtedly really pumping and you are not a calm, collected, reliable observer. Third, eyewitness sightings of rare, brief events, are notoriously inaccurate. But the most important reason may simply be that humans cannot judge distance well, especially at the large distances of most sightings. A 20 pound bobcat will appear to be the size of a 100 pound mountain lion if you think the distance is only 70% greater than the actual distance (see my personal experience with this). (Also see Wild Animals at the Santa Rosa Plateau for a slightly expanded version of this paragraph.)

These increases in apparently mountain lion sightings have led to general hysteria over mountain lion attacks, and the common conception that something has changed in cougar behavior. However, an extremely simple analysis of the data shows that nothing has changed in cougar behavior at all. The increased number of attacks is explained simply by the increase in the number of people, and the rebound in cougar populations after bounty hunting ceased.

The reason for the increase in attacks and sightings in California is absolutely clear. Estimates of the current population of mountain lions in California are around 5,000 to 6,000, which is probably not far off from what it was prior to the human devastation of their population. By 1971, it was estimated that as few as 600 mountain lions remained in California, a shameful ~90% decrease in the population, all due to humans. As a result, then-Governor Ronald Reagan imposed a moratorium on recreational hunting of mountain lions in 1972. Californians later passed Proposition 117 in 1990, which declared the cougar a "specially protected mammal".

The number of attacks is proportional to the number of people times the number of lions. If the lion population was only 10% of normal during the mid-century, attacks should be only 10% of normal. If the number of people in California has increased by over 20 times, from 1.5 million in 1900 to 35 million in 2000, the attack rate in 2000 should be 20 times the attack rate in 1900. It is thus no surprise at all that there was a long period centered in the mid-1900s where there were no attacks.

See Statistics of Attacks below for more information.

Many people, especially hunters, think that attacks would cease in California if hunting was allowed again. Three simple observations refute that contention:

The only way to eliminate the danger of lion attacks is to eliminate the lions, as we almost did in California in the mid-1900s. That is the humans first, without thinking short-sighted attitude that prevailed in the 1800s and early 1900s, when we eliminated the Grizzly Bear in California (the state animal on our flag!), wolves in most of the U.S., and tried to eliminate coyotes and mountain lions, as dangers to humans.

Since then, we have learned that these animals are vital to our ecosystems, and in the long run, much more harm to humans may come from eliminating them than any short-term harm any of these predators has ever done to us.

One possible example: Mountain lions are the main predators of deer. Without mountain lions, the deer population will explode, along with the ticks that feed on them. This would increase the number of people contracting Lyme disease.

We humans do not yet have the wisdom to know what happens in the longer run by eliminating any element of nature. There are multiple scenarios that any decent scientist can envision that might increase the number of human deaths per year manyfold over that currently due to cougars.

It is all summarized in this quote:

Man should not destroy what man cannot create!

From the Mountain Lion Foundation:

We believe the mountain lion is the foremost symbol of our vanishing wilderness.

As its habitat disappears, so do its chances for survival. When the mountain lion is in peril so is the other wildlife in its ecosystem.

As a society we assume responsibility for the welfare of the mountain lion and other wildlife.

Its survival is a moral obligation.

It would be shameful to eliminate this species to prevent an average of less than one death per year when we kill each other with cars at the rate of 40,000 people per year.

It is important to keep in mind that lion attacks are still extremely rare in California and nationally. For some reason, humans worry much more about rare dangers than about common dangers. Two examples:

So we should be much more worried about meeting a car or the dogs we see every day rather than a mountain lion. Unfortunately, we aren't, because we are much more familiar with being in a car or being around a domestic dog than we are with being around an uncaged mountain lion. Rationally, if one avoids hiking because of fear of mountain lions, one should also avoid driving in a car, crossing a street as a pedestrian, or getting close to our own or anyone else's dog.

Another example: an average of several people per year die from recreational activities in the San Gabriel Mountains, yet no one has ever died from a cougar attack in the San Gabriel Mountains. You are probably much more likely to die from a misstep off a trail than from a mountain lion attack. So pay attention to where you are putting your feet rather than worrying about if there is a mountain lion about to pounce on you!

If you want to virtually eliminate any mountain lion danger to yourself, don't hike alone. All hiking fatalities in California have occurred to single hikers. However, recognizing that the danger is low, I continue to hike alone. Being human, and therefore suffering from the same fear of rare events as everyone else, for a while I carried a big stick, which at least made me feel better. But once I started working on plant lists, my stick was a nuisance, so since early 2001 I stopped carrying it. I typically hike every fourth day, usually alone, and have no worries about mountain lions at all. However, when I see bear scat or claw marks on trees above my head, I definitely worry about bears for a while! After all, you have some hope of fighting off a 100-150 pound cougar, but no chance at all against a 400 pound bear.

See also relative outdoor dangers (the numbers and reference are given in MLCSP), compiled by an expert on cougar attacks on humans, Professor Paul Beier, a wildlife ecologist at Northern Arizona University in Flagstaff. Although one can quibble with his numbers (for example, you can almost completely avoid the danger of death by lightning if you don't hike in Florida or during storms), his point is correct. Considering only outdoor activities, there are many other things to worry about that are more likely to occur than lion attacks, including auto collisions with deer, lightning strikes, bee stings, dogs, rattlesnake bites, and black widow spider bites. (outdoor hazards)

By far the best web reference on mountain lions and people is the Outdoor California magazine special issue on mountain lions, available as a single long page or individual articles.

General Advice About Lion Encounters

The general advice to avoid being eaten by a mountain lion is to travel in groups. If you encounter a mountain lion by yourself or with your children, stop, make yourself look as big as possible, and pick up small children and put them on your shoulders to make you appear even larger. Aggressively defend your position. The idea is to deter their attack by making them think that it isn't going to be easy for them. Pick up a branch or a rock to help fight them if needed. They are just big kitty-cats, so you don't want to appear as smaller prey to them. In particular, running away makes them think you are prey, and will encourage an attack. Yell for help by screaming cougar! or something similarly specific rather than just help!.

Do not take your dog with you into the wilderness, if you want to reduce your chances of a cougar attack. According to Banff National Park Chief Warden Ian Syme, "Many people like to take a dog along in the wilderness because it gives them a sense of security. They feel they will be protected from cougars. But that's not the case. Dogs are an attractant in most cases."

However, you may not have to worry about taking action to prevent an attack, since mountain lions ordinarily either lie hidden, waiting for prey to approach beneath them, or approach unseen, and then attack and kill by a bite to the back of the neck that severs the spinal cord. This was the modus operandi for the attack on Barbara Schoener.

Also see:

Statistics of Attacks

The current reported attack rate in the U.S. and Canada is ~6 attacks per year, with just under 1 death per year. This number has been constant since at least 1991, with no evidence at all that the rate has changed.

YearU.S.A. and CanadaCalifornia
# of Attacks# of Deaths# of Attacks# of Deaths
19914200
19924110
19933020
19949232
19953010
19966100
19977100
19989000
19996100
20008000
20017100
20025000
20032100
total731072
Average per year5.60.80.50.2

Each attack is detailed in the pages linked in the next section.

The numbers above on deaths are most likely highly complete, since deaths rarely go unnoticed.

The numbers above on attacks, however, are most likely underreported, possibly by a significant factor, because a lot of attacks never get reported, or never make it outside of local papers, and hence are not known to us.

Incomplete reporting is the norm for animal attacks. Dog bites, for example, are underreported by an estimated factor of 2 to 5.

I have no idea at all what factor to use to correct for incomplete reporting for mountain lion attacks. My guess would be a factor of two to three.

As mentioned above, these numbers are perfectly consistent with a constant average attack and death rate. Simply due to random variations, one would expect the number of attacks per year to range, 95% of the time, between 1 and 10. The numbers above range from 2 to 9, almost exactly as expected from chance.

This expected variation can easily be computed by anyone who can calculate a square root, and who is told that the standard deviation (a measure of the statistical error) is the square root of the average number. One expects that 95% of the time, the number of attacks should vary from the mean number minus twice the standard deviation to the mean number plus twice the standard deviation. In this case, the expected variation is from 5.6 - 2*sqrt(5.6) to 5.6 + 2*sqrt(5.6), which gives the numbers above when rounded to the nearest integer.

There is a standard statistical test to see if there is any variation in a data set that is beyond that expected from chance, the chi-squared test. In this case, the chi-squared test immediately shows that these numbers are dead consistent with those expected from random variation, and thus that there is no more information in these numbers. It is statistically meaningless to claim that the attack rate, or the death rate, has varied in the U.S. and Canada since 1990.

This consistency with expected statistical variation also implies that the completeness of reporting has not changed significantly since 1990, at least within the precision of the data.

The main reason I went into such detail about the statistics here is to give the reader a good idea that the best statistics on attacks available, that for the entire U.S. and Canada, shows no evidence for any variation since 1990. If one attempts to break the numbers down for a smaller area, such as California, the statistical variation due to chance is so large that it is utterly meaningless to try to deduce any information other than the mean rate since 1990.

Thus in California, there is an average of one attack every two years, and one death every five years. Statistically, with rates this low, one would expect a number of years to go by without an attack, and even more without a death. There is no further information in the California attack numbers in the last several decades.

I can, however, easily compute the expected attack rate in the mid-1900s. The attack rate should be less by a factor of at least ~600/5500 (the ratio of the number of cougars in the mid-1900s to the number today) times another factor of 15 million / 35 million. This is a minimum factor, because we have not just increased our population in California; we have significantly expanded our homes into mountain lion territory, as well as opened up a number of recreation areas in mountain lion territory that were not open to the public in the mid-1900s. This minimum factor is 0.11 * 1/7 = 0.047.

The resulting maximum attack rate is then 0.047 * 0.5 = 0.02 per year, or one attack every 50 years. It is no surprise at all that there were no attacks in the 77 years from 1909 to 1986.

For completeness, I have collected some summary information on attacks from other sources. However, keep in mind the above statistical analysis when you read them.

List of Mountain Lion Attacks

List of Mountain Lion Attacks On People in California

List of Mountain Lion Attacks On People in the U.S. and Canada not including California

Bibliography on Mountain Lions

Source Abbreviations

AbbreviationSource
CWRColorado Wildlife Report, 10/22/97
LATL.A. Times
MLCSPMountain Lions and California State Parks
OC1995 Outdoor California magazine special issue on mountain lions: DFG single long page or individual articles
OCROrange County Register
PSNPasadena Star-News
SDUTSan Diego Union-Tribune
TPTerm Paper On Mountain Lions


I thank Jane Strong for several of the links given above, and motivating me to finally write this webpage, after gathering the information for years.


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Copyright © 1999-2006 by Tom Chester.
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
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Comments and feedback: Tom Chester
Updated 28 February 2006