The mother will defend her cubs by fighting with every ounce of her strength, but prefers to avoid predators (adult males, man, wolves) by running away. Conflict behavior includes hissing, growling, roaring, boxing, jaw chomping, biting, clawing.
It doesn't have any predators and is the second largest bear on the planet. It is similar to asking how does a lion or an Orca defend itself: By killing and eating whatever was dumb enough to attack...
Because They Live In Snowy Areas. Snowy Areas Such As Antartica And The Arctic Are Very Snowy Areas. Polar Bears Live In Arctic. So Don't Be Fooled When You Think That Polar Bears Eat Penguins....