3 Facts about bears and lady business

Good news for ladies who like the woods—your period is (probably) not something that attracts (most) bears.

There are not a lot of studies addressing this particular topic, but a National Park Service paper published this year took a look at all of them and put the scattered pieces information together into a single puzzle. It's probably not a complete picture, but it's certainly better than hearsay and random, sexist stories you heard from your grandpa's drinking buddy. More importantly, even when there is a documented risk between menstrual blood and bears, that shouldn't be construed as a reason to keep women out of the wilderness. After all, bears are attracted to food, and we don't tell people they shouldn't eat while backpacking. Instead, we have practices that reduce risk. Same thing applies here.

Here's what we learn:
1) You can menstruate freely and without fear in the contiguous 48 United States. Grizzlies, and particularly black bears, don't seem to be interested in what's happening in your pants. Evaluating hundreds of grizzly attacks found no correlation between menstruation and risk of attack. In the case of black bears, this has actually been tested experimentally, with researchers leaving used tampons from various stages of menstruation out in the wilderness and watching how the bears respond. (Science!) The bears completely ignored the tampons.

2) Yellowstone data suggests food is a much bigger risk than menstruation. Analysis of bear attack data from Yellowstone National Park doesn't even consider attacks that happened before 1980. Why? Because that was before stringent rules on in-park food storage and bear feeding. The vast majority of pre-1980 attacks are already known to be related to bears seeking out human food. Meanwhile, between 1980 and 2011 only 9 women have been injured by bears in Yellowstone. Of those, six were incidents where women and bears ran into each other unexpectedly on hiking trails. In the other three incidents, which didn't rely on the element of surprise and are, thus, more likely to have attraction factors involved none of the women were menstruating at the time of the attack.

3) Polar bears are a whole 'nother story. Two different polar bear studies, one in captivity and one in the wild, have shown that those bears are attracted to human menstrual blood—even more than plain old human blood that wasn't related to menstruation. They are also attracted to the scent of seals and (again) human food.

Big picture: Food still seems to be a bigger issue in bear attacks than menstruating ladies. And, as with food, the Park Service has guidelines that you can follow for how to best deal with tampons while in the wilderness.

Read the full National Parks Service report, including the safety guidelines for women on their periods

Via Mother Nature Network


  1. Weird coincidence.  Was watching Nova’s “Bears of the Last Frontier” last night, which got me curious about attacks, which got me on the google…   Now this on Boing Boing today..

  2. “You can menstruate freely and without fear in the contiguous 48 United States.”

    Yes, but where are the studies on Hawaiian polar bear attacks?

        1. I must agree Cows are the new sharks. In fact it is well known that Cow fin soup helps with virility, lactose legitimacy and helps memory lose. I think.

  3. I’m sort of surprised that this is necessary. Is it really still “common sense” or whatever that menstrual blood or menstruating women attract bears?

    I’ve been hiking, mountaineering, climbing, etc. since about the mid-late 90’s. I’ve spent LOTS of time in areas with black bears, and some time in areas with grizzly bears (including about a solid month in griz territory in AK). The only time women/menstruation/bears comes up is as an “old wive’s tale” that’s utter nonsense and which no sensible person should believe. In short, I thought we debunked this nonsense over a decade ago.

    That’s not to say that used menstruation products don’t require careful handling and disposal in bear country. They certainly do. It’s just that they get the exact same treatment as food, and really anything else scented and potentially tasty (toiletries, lip balm, sun screen, etc.)

    1.  Old wive’s tales die hard, and not everybody is a seasoned mountaineer or even a casual camper.  Go out on the street and ask people the best actions in response to surprising a bear in the wild and am sure the variety of answers would be very interesting/funny. 

  4. “1) You can menstruate freely and without fear in the contiguous 48 United States.”

    Best line on the internet this morning.  But what about Hawai’i and Puerto Rico?

  5. When I’m tramping with the Missus during her special time I use a custom sling to haul her high into a nearby tree. If we’re in grizzly country I’ll set camp well away from her oestral miasma. We communicate via little Cobra walkies, aka our little “nuzzleboxes.”

    It just makes good sense.

  6. Paint me a sexist, I thought this was true. After all, Myth Buster’s never mentioned it. 

    At about 1300 lbs, the polar bear is not surprising the only bear that seeks out any blood scent as possible food source. Average seal weights 350 lbs. An average human would be a snack at 180-220. Although, polar bear probably avoid skinny humans as too many bones, not enough meat.

  7. From what I’ve heard from zoologists, bears can’t digest women who are menstruating. If it’s a legitimate bear attack, the female body has ways to try to shut that whole thing down.

  8. Well, This is great news! I can’t wait to tell my wife we don’t have to tie her 7 feet up a tree and 7 feet out on a limb at night any more.

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