The question of whether bears are attracted to menstruating women has persisted in wilderness lore for decades. This concern gained widespread attention following a tragic 1967 incident in Glacier National Park, which led to speculation that menstrual odors may have provoked the grizzly bear attacks. Moving beyond speculation requires a look at the scientific evidence and the biological realities of bear behavior to separate persistent myth from established fact.
The Scientific Consensus on Menstrual Scents
The scientific community has investigated how different bear species respond to menstrual odors. Studies focusing on the North American black bear concluded that they essentially ignore these scents. In a 1991 field experiment, researchers presented free-ranging black bears with used tampons and observed their reactions to menstruating women; none of the bears showed appreciable interest.
Analysis of hundreds of grizzly bear attacks in North America, including the famous 1967 events, similarly found no evidence linking menstruation to aggressive encounters. The bears involved in the Glacier National Park incident were found to be “food-conditioned,” meaning they had lost their natural fear of humans after associating people and campsites with easy access to food and garbage.
The only notable exception involves polar bears, which are obligate carnivores focused on marine mammals. A 1983 study found that captive and wild polar bears responded strongly to used tampons, often consuming them, while ignoring non-menstrual human blood. This reaction suggests a unique attraction, likely due to the blood’s protein content, but researchers cautioned that this does not translate to an increased risk of attack, as the bears generally avoided the physical presence of the women.
The Power of Bear Olfaction
The persistent concern stems from the bear’s extraordinary sense of smell, which is their primary tool for navigating the world and locating food. A bear’s brain dedicates a much larger proportion of its capacity to scent processing than a human’s, possessing an olfactory bulb estimated to be five times larger. This neurological hardware, combined with a convoluted nasal structure, gives bears an olfactory acuity estimated to be 2,100 times better than a human’s. Bears are classified as macrosmatic animals, meaning they rely heavily on their sense of smell to detect food from miles away.
Bears are constantly searching for high-calorie, easily accessible food sources, including fats, sugars, and garbage. Their remarkable nose is not selectively tuned to human menstrual blood, but rather to any strong odor that might signal a potential meal. This means that scented toiletries, cooking fumes, or improperly stored food are far more likely to trigger an investigative response than the subtle odor of menstruation.
Essential Safety Practices in Bear Habitats
Since a bear’s powerful sense of smell makes it highly sensitive to all foreign odors, the focus for safety shifts from menstruation to comprehensive scent management. All potential attractants, including food, garbage, and scented toiletries like toothpaste and soap, must be secured. In the backcountry, this means storing all scented items in certified bear-resistant canisters or hanging them at least 10 to 15 feet off the ground and four feet from the tree trunk.
Campers should establish separate zones for sleeping, cooking, and food storage, ideally placing them at least 100 yards apart. Never sleep in the clothes worn while preparing or eating food, as residual odors are a strong attractant. When hiking, making consistent noise helps alert bears to human presence, preventing surprise encounters. Carrying and knowing how to use bear spray is an effective defense measure for close-range encounters.
Menstrual products should be managed as another form of scented human waste. Used tampons or pads should be placed in double-sealed plastic bags and stored with other garbage inside a bear-resistant container. The key to safety in bear country is minimizing the presence of any non-natural odor that could lead a foraging bear to associate humans with a food reward.