Black vs grizzly/brown bears (and it can be difficult to tell the difference, or may be obvious)
Typically a black bear is not as brave and if it actually attacks you it may scare it off by fighting. Play dead, if it bites, fight back. It may charge but if it bites, you have a problem.
Brown bears, grizzlies don't scare, typically, so playing dead is the advice, unless it wants to eat you or starts hauling you away. Typically a brown/grizzly will attack them once it determines you are "dead" will go away. A bear wandering past a tent might decide to take a bite out of something laying against the wall so the advice is don't pack your tent so tightly you will touch the wall at night.
There are 2 basic categories of attacks.
Provoked attacks include bear with cubs or yearlings or 2 yr olds, defending a food source, just plain startelement, though you may not know what provoked it. Stay calm, speak quietly, back away, don't make direct eye contact but keep talking quietly and backing away slowly, drop @ last sec to curl on belly/side in fetal position with hands behind neck.
Then there are predatory attacks, where the bear considers you food. You may notice a bear stalking you and includes night attacks since you have done nothing to provoke them. This includes bears habituated to humans through food, garbage, etc who have that little switch in their head click "food?" and just plain nutso bears (bears are like humans in that they have a few nasty ones).
Though this guy advises guns though sometimes spray (and true, it depends on where you are), he spells out the difference between bears decently. Of course there are bears that don't act typical, this is more of a broad guideline.
http://www.arcticwebsite.com/BearSurvival.htmlThe Black Bear:
The black bear is the smallest of the bears. He is primarily a scavenger, not a hunter. In areas where people are present he has learned that people can provide food, and he may have lost much of his fear of man. Use the procedure as above, but if he attacks it is likely that he has mistaken you for food, or that you have food, or he could be rogue. Play dead, but if he bites, fight back.
The Grizzly Bear:
The grizzly bear is indifferent to man. He as no fear of man and will attack if he feels like it. Sometimes he may not attack and may run away. The best thing is to avoid him and never surprise him. If he does attack he rarely sustains his attack, after you play dead. Remember he is a very big animal and his weight alone can kill.
The Polar Bear:
The polar bear is the most deadly of all. While his normal food is seal, they have been known, for centuries, to attack humans. Until the introduction of firearms, the native people of the north have lived in fear of them. Many early explorers have told horror stories of polar bear attacks. These bears are known to stalk and hunt humans. If you are in polar bear country carry a firearm or avoid the area.
http://www.mountainnature.com/wildlife/bears/bearencounters.htmPredatory Encounters. While this is a rare situation, and generally refers to predatory attacks by black bears, this can be a very serious encounter. Since the bear is hunting you as prey, you must be prepared for an imminent attack. The bear may circle you, slowly moving in closer and closer until it decides whether to attack or not.
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If a black bear (or any bear that is stalking you) makes contact. If the attack escalates and a black bear (or any bear that appears to have been stalking you) physically contacts you, fight back with anything that is available to you. Black bears tend to be more timid than grizzlies and fighting back may scare the bear off. In addition, if a bear is stalking you than you are in a predatory situation and fighting back is your only option. This also applies to any attack at night as these may also be considered predatory in nature.
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If a grizzly makes contact. As above, if you believe the bear to be stalking you, fight back with everything you have. In general though, playing dead in a daytime grizzly encounter tends to reduce the level of injury sustained by most attack victims. Many grizzly attacks are defensive in nature, and playing dead may show the bear that you are not a threat.
http://www.wikihow.com/Escape-from-a-BearIf any bear makes a predatory attack or you receive any attack from a black bear: Fight back. Fight a black bear attack or any predatory attack. If the bear is a black bear, or if you have determined that the bear sees you as food (this is actually quite rare, and more common with black bears and, some say, polar bears than with grizzlies), your only chance of escape is to fight it or scare it away. Hit the bear with rocks, pots, pans, sticks or fists—anything handy, really. The odds may seem against you in a fight, but bears generally do not see humans as prey, and a bear that makes a predatory attacks is usually immature, starving, or wounded, and may easily be scared away if you hit it.
I grew up terrified of bears, knowing that there was a bear with my name written across its brain. Over the yrs, living and camping where bears lived, I grew used to them and very much like them. I have startled a mom with young cubs (oh mama bear I am so sorry, while backing off) and one with a 2 yr old who shook the bushes at me and growled loud and sure startled me back. I backed off apologizing intensely. I've walked down a trail in AK to come to a sudden stop since someone was watching me closely in the dense brush. Talking quietly, telling bear I'm just passing through, am glad you share your space and walk quietly and slowly on. Came back 5 min later to find huge tracks walking the way I was now going. Nice bear, good bear.
Bears are very cool, though it will be interesting to find out what happened with this attack since it is far outside the norm.
Finally, another bear story:
http://www.nydailynews.com/news/national/2010/07/29/2010-07-29_nh_bear_nibbles_montana_bruin_kills.html