How Do Black Bears Respond to Menstrual Odors?

Despite a widespread misconception that menstrual odors attract black and grizzly bears and precipitate attacks, there is no evidence for this.

The misconception began in 1967 when grizzly bears killed a menstruating woman and a woman who was approaching menstruation in Glacier National Park. It was known that some dogs are attracted to menstrual odors, so government agencies began warning women not to enter bear country during menstruation.

How did people learn that this concern was unwarranted?

For grizzly bears, Herrero reviewed the attacks on the two women plus hundreds of other attacks and found no evidence that menstruation was a factor.

For black bears, field tests by Ely researchers showed that the bears ignored menstrual odors regardless of the bears’ age, sex, or reproductive status. In addition, Cramond, Herrero, and Ely researchers reviewed black bear attacks across North America since 1900 and found no instance of a black bear attacking or being attracted to a menstruating woman. After attacks, investigators routinely ask women about menstruation.

On 20 February 1989, Ely researchers asked over 300 bear biologists at the 8th International Conference on Bear Research and Management in Victoria, British Columbia, about black bear attacks. None of the biologists had ever heard of a black bear attacking or being attracted to a menstruating woman.

For polar bears, Cushing offered used tampons, seal meat, and non-menstrual human blood to captive polar bears. The bears usually ate the used tampons and seal meat but ignored the non-menstrual blood, which suggests a preference for menstrual blood in that species.