JWM: In freezing cold or wind, bear spray still works

By Joshua Rapp Learn

A ranger deploying an inert can of bear spray in Yellowstone National Park. Credit: NPS/Neal Herbert

For Tom Smith, bears weren’t the real danger — the spray used to deter them was. But despite his own experiences with temporarily burned eyes, some serious coughing, and dealing with freezing temperatures while spraying the deterrent, his research has revealed that bear spray definitely works.

“We’re spraying that stuff, and next thing you know, you hear people coughing,” said the wildlife science professor at Brigham Young University and the lead author of a study published recently in the Journal of Wildlife Management.

Smith had heard all kinds of urban legends about bear spray for years — everything from it not working in cold temperatures or windy conditions to the repellent spraying back on the people trying to protect themselves from bears that get too close. In some cases, people just thought that “something in a can like this isn’t going to stop a 500-kilogram bear,” Smith said.

Some people in northern countries that have higher numbers of polar bears (Ursus maritimus) or brown bears (Ursus arctos) had an “alarming disregard” for even considering using the stuff, and many people just didn’t carry it due in part to some of these misconceptions.

“The outcome [in some of these situations] was awful,” Smith said — some people who didn’t carry or use bear spray were killed.

But nobody had ever scientifically tested the bear spray to see if some of these rumors about it were true. Smith and his colleagues took on the challenge. They tested bear spray cans in a variety of conditions, and also conducted modeling and calculations to tell how well the spray was going to perform.

They found that based on records of bear encounters in Canada and the United States, bear spray was about 90% effective in deterring northern bear species. But they still wanted to see if certain conditions diminished its efficacy.

For one of their tests, they sprayed the cans in the wind. One idea commonly mentioned by people in northern areas is that the bear spray might blow back on the person using it, stopping it from doing anything to deter an approaching bear.

Smith and his team learned that this was partly true — the wind ended up blowing the spray back in their eyes. It caused some pain and coughing. And while their eyesight was good enough to get to the nearest outdoor restroom, it wasn’t good enough for them to see they had accidentally gone into the women’s side.

“We had some interesting times with that stuff,” he said.

Still, they weren’t sure whether the power of the spray leaving the nozzle was enough to reach bears even against the wind. Instead of accidentally spraying each other again, they took to modeling the situation mathematically in different wind directions.

They found that even against strong wind, the bear spray would travel for at least two meters. If the bear is close enough, “you’re still going to hit him” and cause some pain, he said.

He noted that conflicts with bears in strong winds aren’t as likely anyway. Bears don’t move around much when wind is stronger than 22 miles per hour, since they can’t smell what’s around them as well as they could in calmer winds.

“A lot of bear attacks don’t occur in the wind,” Smith said, adding that most bear attacks occur when people surprise bears — something that doesn’t happen on windy open tundra or plains. Even on windy days, gusts are less likely to be strong in forests or thicker bush.

The spray worked much better with crosswinds, or when the wind was blowing perpendicular to the person, and when the wind is behind the user, though. Overall, the records showed that of the 156 people who used bear spray in windy conditions, only 14% said that the spray didn’t go where they wanted it to, or it blew back on them. And only 2% reported an injury from the spray.

“Wind is an issue, but it’s not a big issue,” Smith said, adding that the chances are low both that a bear will be out in such winds, and that it will be coming at the user with the wind.

The researchers had also heard a number of rumors about the spray not working when it got too cold. Some people complained it would just dribble out like a liquid rather than spraying as an aerosol.

But when they tested the cans under a number of different cold temperatures, they found that it still worked at least down to -23 degrees Celsius. However, the sprays range did drop to about 4 meters at that temperature compared to its normal 10-meter range.

In any case, Smith said that these arguments about the cold don’t necessarily hold a lot of weight either. That’s because people would probably keep cans in their coat or sleeping bag where body temperature would keep it warmer. That being said, he advised people against storing cans outside in the winter.

One of the major problems overall, Smith believes, is that people are always testing their cans, spraying them to see if they work. The problem is this naturally decreases the pressure. “That’s another one of those boneheaded lame ideas,” Smith said. “You get a very rapid loss of head pressure. That should be no surprise to anybody, if you’ve ever had a can of whip cream.”

Overall, Smith said that his testing shows that most of the myths about bear spray don’t hold a lot of water.

“Can it stop a bear? It most certainly can. Does the wind affect it? It can, but not in a way that’s going to make it ineffective,” he said.

He has little time for some of the other problems people have, such as the cost of the cans.

“It’s not anywhere near as expensive as getting 300 staples in your face,” he said. “How cheap can you be?”

This article features research that was published in a TWS peer-reviewed journal. Individual online access to all TWS journal articles is a benefit of membership. Join TWS now to read the latest in wildlife research.

Joshua LearnJoshua Rapp Learn is a science writer at The Wildlife Society. Contact him at jlearn@wildlife.org with any questions or comments about his article.

Read more of Joshua's articles.


Share your thoughts on this article, and others, on our Facebook and Twitter pages.