GOT YOUR DOUBTS that a 225-gram can of bear spray could stop several hundred kilograms of charging muscle and fur?

Until recently, renowned Canadian bear expert Steve Herrero shared those doubts. But then he and colleague Thomas Smith, a wildlife scientist at Utah’s Brigham Young University, took a hard look at bear encounters in Alaska from 1985 to 2006 in which pepper spray was used.

Bear spray stopped aggressive ursids in 92 percent of cases, says Herrero, professor emeritus of environmental science at the University of Calgary.

Preliminary results from an unpublished study by Smith and Herrero suggest that guns, on the other hand, were effective only about 67 percent of the time. Herrero cautions that variables such as gun type, ammunition and the shooter’s skill can all influence the outcome.

The problem with guns, says Herrero, is that when a bear is charging, it’s hard to think straight, much less shoot straight. “It’s infinitely easier to aim a can of bear spray,” he says. “It disperses into a cloud, and you can aim that cloud.”

It’s also infinitely better for the bear. “That’s very, very important,” says Herrero. “The effects, while totally immobilizing, are totally reversible.”