We tend to think that encounters with bears are fun thing. This is true when you are in a car watching bears at roadside.

But a single bear is silently following you and you are alone, he may be predatory and there is a definite danger. Don't panic and run as you can not outrun a bear, but stay there or climb up a tree, or fight back.

The followings are pieces of facts about human encounter with black bears.

Though black bears rarely kill or seriously injure people, when they do, it's most often the result of predatory behavior by males inside their wilderness home ranges and not by females protecting cubs or animals defending a carcass, said Dr. Stephen Herrero, professor emeritus at the University of Calgary and author of the classic Bear Attacks: Their Causes and Avoidance.

"Most fatal black bear attacks were predatory and all fatal attacks were carried out by a single bear," Herrero said in a U-Cal story. "With training, people can learn to recognize the behavior of a bear that is considering them as prey and deter an attack by taking aggressive action such as fighting back."

"Each year, millions of interactions between people and black bears occur without any injury to a person, although by 2 years of age most black bears have the physical capacity to kill a person," they wrote.

"In particular, the common belief that surprising a mother bear with cubs is the most dangerous kind of black bear encounter is inaccurate," Herrero said. "Instead, lone male black bears hunting people as a potential source of food are a greater cause of deadly maulings and related predatory attempts."

Other insights:

• No fatal attacks involved more than one bear, and almost all were adult males.
• Bears that have previously killed are most likely to act aggressively again.
• People traveling or camping alone were the mostly likely victims — almost 70 percent of the fatalities involved single person. Only 9 percent of attacks occurred with more than 2 people present.
• Human food and garbage tended to attract aggressive black bears and might increase the likelihood of a serious bear attack.
• The victims were ranged from small children to old people. No single activity or region correlated with the fatal attacks. “The widespread geographic distribution of fatal attacks suggests that they may occur in a variety of bear habitats and bear population conditions,” the authors wrote. “Fatal attacks do not appear to be associated only with a specific black bear population, geographic area, or habitat.”
• Fatal attacks were most numerous in August — when black bears are shifting into overdrive to put on weight for the winter. Most attacks occurred during the day, with about 60 percent in the backcountry and 40 percent closer to communities.
• None of the victims used bear spray. “Nor was bear spray available for other party members to deter the attacking bear,” the authors wrote, adding: “Two studies of the effectiveness of bear spray that had capsaicin as its active ingredient demonstrated its effectiveness but noted possible interference with wind.”

Recognizing the difference between a predatory attack and defensive, fearful activity -- and possibly wielding a fresh can of bear spray -- may be the crux of protecting oneself against a fatal attack by a determined blackie.

Beware the bear that stalks in silence:
Potentially predatory approaches are typically silent, and may include stalking or other following, followed by a fast rush leading to contact. We know of incidents where a black bear behaved as if it were considering or carrying out a predatory attack and was deterred by people’s aggressive actions such as shouting, or hitting with rocks, fists, or sticks. Once predatory behavior is initiated it may persist for hours unless it is deterred.

Faced with this chilling, single-minded tableau, people should use "all possible deterrents such as bear spray, loud noises, fists, firearms, rocks, knives, or clubs," the authors wrote. Do not run away as it will suddenly create bear's predatory instict.

At the same time, if a black bear acts stressed or shows "defensive threat" behaviors -- swatting the ground, mounting short charges, clacking teeth, making huffing or growling noises -- it's much less likely to attack. Again, do not run but stay firm there or back up slowly. When given a space and time for the bear to escape, the bear will most likely retreat.