the evening of August 13, 1967, two women were attacked and killed
by grizzly bears (Ursus arctos horribilis) in separate incidents
within Glacier National Park (GNP). Following these incidents, there
was speculation that due to odors associated with menstruation,
women may be more prone to attack by bears than are men (Rogers
et al. 1991).
The objective of this paper is to present the data available
on this subject so that women can make an informed choice when deciding
whether or not to hike and/or camp in bear country during their
In a study
designed to test the hypothesis that bears are attracted to the
odors of menstruation, Cushing (1983) reported that when presented
with a series of different odors (including seal scents, other food
scents, non menstrual human blood, and used tampons), four captive
polar bears (Ursus maritimus) elicited a strong behavioral response
only to seal scents and menstrual odors (used tampons).
Cushing (1983) also reported that free-ranging polar
bears detected and consumed food scent samples and used tampons,
but ignored non menstrual human blood and unused tampons. This suggests
that polar bears are attracted to odors associated with menstrual
analyzed the circumstances of hundreds of grizzly bear attacks on
humans, including the attacks on the two women in GNP, and concluded
that there was no evidence linking menstruation to any of the attacks.
The responses of grizzly bears to menstrual odors has not been studied
al. (1991) recorded the responses of 26 free-ranging black bears
(Ursus americanus) to used tampons from 26 women and the responses
of 20 free ranging black bears to four menstruating women at different
days of their flow.
Menstrual odors were essentially ignored by black bears
of all sex and age classes. In an extensive review of black bear
attacks across North America, no instances of black bears attacking
or being attracted to menstruating women was found (Cramond 1981,
Herrero 1985, Rogers et al. 1991).
National Park Bear-Caused Human Injury Statistics
Over 62 million
people visited Yellowstone National Park (YNP) during the 23 year
period from 1980 through 2002. These visitors spent over 15.4 million
use nights camping in developed area campgrounds and over 956,000
use nights camping in backcountry areas within the park. Although
actual statistics are not available, many menstruating women undoubtedly
visit, hike and/or camp within YNP each year.
During the 1980-2002 time period, 32 people were injured
by bears within YNP, an average of only 1.4 bear-inflicted human
injuries per year (Gunther 2003).
There was no evidence linking menstruation to any of
these 32 bear attacks. Of these 32 injuries, 25 (78%) were men,
and 7 (22%) were women.
the 7 women injured by bears, most (57%, n=4) involved surprise,
close encounters between bears and women that were hiking and were
therefore probably unrelated to menstruation.
3 (43%) incidents surprise encounters were not involved. Of these
3 incidents, 1 involved a female (non-menstruating) jogger in a
developed area that was slowly approached then bitten by a grizzly
bear, 1 (6%) involved a female Park Ranger moving an injured bear
that had been hit by a car off of the road (thus was probably not
related to menstruation), and 1 involved a woman (non-menstruating)
in a tent in the backcountry.
It is difficult to accurately compare the ratio
of males to females that are injured by bears because the park does
not keep records of visitor use of the park by gender. However,
the injury data for YNP does not suggest that females are more likely
to be attacked by bears than are males (Gunther and Hoekstra 1996).
there is no evidence that grizzly and black bears are overly attracted
to menstrual odors more than any other odor, certain precautions
should be taken to reduce the risks of attack.
The following precautions are recommended:
1. Use pre-moistened, unscented cleaning towelettes.
2. Use internal tampons instead of external pads.
3. Do not bury tampons or pads (pack it in - pack
it out). A bear may smell buried tampons or pads and dig them up.
By providing bears a small food "reward", this action
may attract bears to other menstruating women.
4. Place all used tampons, pads, and towelettes
in double zip-loc baggies and store them unavailable to bears, just
as you would store food. This means hung at least 10 feet above
the ground and 4 feet from the tree trunk.
5. Tampons can be burned in a campfire, but remember
that it takes a very hot fire and considerable time to completely
burn them. Any charred remains must be removed from the fire pit
and stored with your other garbage. Also, burning of any garbage
is odorous and may attract bears to your campsite.
6. Many feminine products are heavily scented.
Use only unscented or lightly scented items. Cosmetics, perfumes,
and deodorants are unnecessary and may act as an attractant to bears.
7. Follow food storage regulations and recommendations
so you can avoid attracting a bear into your camp with other odors.
All odorous items that may attract bears, including food, cooking
and food storage gear, toiletries, and garbage, must be kept secured
methods for storing bear attractants include:
1.) in a vehicle (the
trunk of a car or cab of a truck)
2.) in a solid camping trailer that is constructed of non-pliable
material (never in a tent or tent trailer)
3.) in a food storage box (provided at some campgrounds), or 4.)
suspended at least 10 feet above the ground and 4 feet horizontally
from the tree trunk.
whether menstruating women attract bears has not been completely
answered (Byrd 1988).
There is no evidence that grizzlies are overly attracted
to menstrual odors more than any other odor and there is no statistical
evidence that known bear attacks have been related to menstruation
(Byrd 1988). However, park visitors have been injured and killed
by bears (Gunther and Hoekstra 1996).
If you are
uncomfortable hiking and camping in bear country for any reason,
you should probably choose another area for your recreational activities.
Byrd, C.P. 1988. Of bears
and women: Investigating the hypothesis that menstruation attracts
bears. M.S. Thesis, Univ. Montana, Missoula. 129pp.
Cramond, M. 1981. Killer bears. Outdoor Life Books. Charles Scribner's
Sons, New York, N.Y. 301pp.
Cushing, B. 1983. Responses of polar bears to human menstrual odors.
Int. Conf. Bear Res. and Manage. 5:270-274.
Gunther, K. A., and H. L. Hoekstra. 1996. Bear-inflicted human injuries
in Yellowstone, 1970-1994, a cautionary and instructive guide to
who gets hurt and why. Yellowstone Science 4(1):2-9.
Yellowstone National Park bear-related injuries/fatalities. Inf.
Pap. No. BMO-1. U.S. Dep. Inter., Natl. Park Serv., Yellowstone
National Park. 2pp.
Herrero, S.M. 1985. Bear attacks - their causes and avoidance. Winchester
Press, New Century Publishers, Inc., Piscataway, N.J. 287pp.
Rogers, L.L., G. A. Wilker, and S.S. Scott. 1991. Reaction of black
bears to human menstrual odors. J. Wildl. Manage. 55(4):632-634.
Kerry A. Gunther
Bear Management Office Wildlife Biologist
Yellowstone National Park May 2002