I think with regard to understanding the way of bears it's important to pay attention to the findings of Northern explorers when North America was largely untouched. Explorers such as J.W. Tyrrell, Samuel Hearne, Fredrick Schwatka and mostly the Natives and the Eskimos, not Daniel Boone or Davy Crockett!
Anyway, here's what J.W. Tyrrel says of the Polar Bear in 1885 in his book,"Across the Sub- Arctics of Canada."
"The Polar is admittedly the monarch of the north. He is the bear of bears, being described by all Arctic travellers as possessing enormous strength and great voracity. Of the scores of polars whose more or less intimate acquaintance I have had occasion to make, I have seen at least two whose tracks in the snow measured fifteen by eighteen inches, whose length measured over nine feet, and whose slain carcases tipped the steelyard at from fifteen to sixteen hundred pounds.
Consequently I have always had great respect for the sentiments expressed in the following lines by an author whose name I regret being able to recall:
"Of the black bear you need not be afraid,
But killing white ones is a dangerous trade.
In this be cool,and well direct your lead,
And take your aim at either heart or head;
For struck elsewhere, your piece not level'd true,
Not long to live your erring hand to rue."
J.W. Tyrrel describes several very interesting accounts of polar bear hunting in his book I mentioned above.
John