Yellowstone Bear Biologist Debunks Myth That Menstruating Women Attract Bears

Yellowstone's bear biologist says menstuating women don't need to overly fear grizzlies in the park's backcountry. USFWS photo.

Editor's note: Ruffin Prevost, long a reporter who covered Yellowstone and Grand Teton national parks for newspapers, now oversees a blog dedicated to those parks: Yellowstone Gate. From time to time we'll share his stories with Traveler's readers, and we invite you to check out Yellowstone Gate.

A report by a Yellowstone National Park bear specialist allaying misplaced concerns that menstruating women might be at greater risk of bear attack has been drawing headlines this month, perhaps as much for its unusual subject matter as for its findings.

Initially covered August 9 on the Mother Nature Network, an online news site about nature and the outdoors, Bears and Menstruating Women is a two-page informational paper prepared in February by Kerry Gunther, a bear biologist who leads Yellowstone’s bear management program. Gunther’s report, one of several regular updates he has issued on the matter, states that “there is no evidence that grizzly and black bears are overly attracted to menstrual odors more than any other odor.”

The Mother Nature Network story has since been referenced or reprinted on several other websites, including Huffington Post and Mother Jones. Within two weeks, Gunther’s brief has attracted a broad and diverse audience, including many urban readers who probably have more to worry about from a possible cataclysmic asteroid strike than a potential grizzly bear attack.

“I have no idea why there has been such an increase in interest about this subject in the last two weeks,” Gunther said by email Wednesday. “Bear attacks always draw a lot of interest, and people are always speculating on the causes of bear attacks.”

Two bear attacks that drew a great deal of interest more than four decades ago was when two menstruating women were coincidentally killed by grizzly bears in separate incidents on the same night in Glacier National Park. Following those attacks in 1967, National Park Service officials in Glacier and elsewhere began warning women to avoid the backcountry while menstruating.

At that time, Yellowstone Park began distributing a brochure that stated “women should stay out of bear country during their menstrual period,” Gunther said.

Since then, the subject has been one of fluctuating interest among hikers and backpackers. Gunther has tracked the scientific literature for the past several years to help inform park visitors and to continue to address fears that were fueled, in part, by Park Service advice after the Glacier attacks.

“We get a few legitimate questions on this subject each year from concerned women who have heard about this issue and are doing their homework before hiking or camping in bear country,” Gunther said.

“We are not spending time or budget on further research on this subject,” Gunther said. “We are only tracking the issue and scientific literature and updating the information we distribute as needed.”

While one study in 1983 yielded results that suggest that polar bears are “attracted to odors associated with menstrual blood,” there is “no evidence linking menstruation to any of the nine bear attacks on women” since 1980 in Yellowstone, Gunther writes in his brief.

He does recommend a few precautions, including: using tampons instead of pads; burning tampons or packing out tampons and wipes in double zip-lock bags; and using only unscented hygiene or personal care products.

Perhaps more importantly, Gunther’s report also recommends reducing risks in bear country by taking five simple but important precautions: hiking in groups of three or more people; staying alert; making noise in areas of poor visibility; carrying bear spray; and not running during bear encounters.

Also in his report, Gunther puts the probability of being injured by a bear in Yellowstone for men and women combined at 1 in 2.1 million.

Those odds seem pretty good compared to driving on an urban freeway, or even eating too many fatty foods. Yet concerns about bear attacks continue, and typically spike after each high-profile incident. Even the menstruation issue is still alive, including references in popular culture, 45 years after the deaths in Glacier Park.

“It takes a long time for myths to die,” Gunther said.

Ruffin Prevost is founding editor of Yellowstone Gate, an independent, online news site offering community news and inside views about Yellowstone and Grand Teton national parks and their gateway communities.