In absolute terms, a 1,500 lb grizzly bear is 40-times stronger than the average man, and 4-times stronger than a 500 lb silverback gorilla. ... The grizzly boar would ruin the silverback gorilla in a complete no-contest. Even if a grizzly bear is the same weight as a gorilla, it will still have the strength advantage.
"If it's a fight between a 1,200-pound male polar bear and a 600-pound grizzly, I think we know who would win," Dr. Rockwell said. "But in this likeliest of cases, it's debatable. There are actually reports in the literature where grizzlies have killed denning polar bear females."Feb 23, 2010