Expert: Jonathan Wright - 2/4/2006

Question
Between a polar bear and a grizzly, which one would be more likely to be defeated in an attack between the two (in other words which one would win?!).

Thank you

Answer
Dear Alex

Thanks for your question. I have found several sites where people speculate over fights between different animals. You must take into account the aggression of individual animals. An aggressive animal could deliver a fatal blow or bite before a passive animal fought back and then it would be too late. Most animals will avoid fighting, as they do not want to risk potential injury or death. Threat displays and similar activities can be used to determine the stronger individual, so the weaker animal can retreat. Many people seem to think that when one species meets another, they engage in a fight to the death. This is of little value to either species, unless one is the predator of the other and is much stronger. Most animals will avoid strong members of another species. Personally, I don't like the idea of animal fights and some of the correspondents in the various websites seem a bit too bloodthirsty for my liking, with some sites showing videos of fights.  

Please note that there is some confusion over the term ‘grizzly bear'. Some people use it for all members of the brown bear (Ursus arctos), including the largest subspecies, such as the Kodiak bear. Other people use it specifically for the subspecies Ursus arctos horribilis. The sites below often do not specify the meaning of the term ‘grizzly bear'.

http://www.lairweb.org.nz/tiger/conflict13.html http://forums.plentyoffish.com/datingPosts113697.aspx, http://forum.ebaumsworld.com/archive/index.php/t-95181.html and http://wiw.org/~jess/archives/2003/12/07/bear-versus-tiger/ contain details of speculative fights between different types of bears. Some people think that brown/grizzly bears will win, while others think that polar bears will win. I'll mention the two species separately.

GRIZZLY BEAR WINS
This is supported by http://www.lairweb.org.nz/tiger/conflict13.html which says that that the grizzly bear is the ultimate carnivore for various reasons. Some of the following have been obtained from other websites.
1. The grizzly bear is more ferocious than other brown bears.
2. It is very strong. If the grizzly and polar bears were the same size, the grizzly bear would probably be stronger, as it is more robustly built, with enormous bone and muscle density. It has powerful arm muscles and a powerful shoulder structure, with a massive hump of muscle on its back that empowers the upper body with massive strength, enabling it to dig in tough ground. The polar bear lacks this hump and has narrower forequarters.
3. It has a shorter, thicker neck and a more heavily built skull. The polar bear is larger, but less robust and has a thinner, longer and more delicate skull.
4. Its huge 6-9 inch long claws can open a carcass; the hook-like claws of the polar bear are 2 inches long.
5. Grizzly bears have been known to fight off polar bears from their feeding areas.
6. The grizzly bear has more power to strike a blow than does a polar bear.
7. The polar bear overheats extremely quickly and would find it difficult to fight for a long time.
8. Compared to a polar bear, it has stronger jaws.

http://www.adn.com/front/story/6415667p-6294323c.html concerns four big polar bears, including three 1,000 lb males feeding on whale carcasses in Alaska. A small, scrappy tundra grizzly sow emerged from the darkness and ambled up the spit, trailed by two yearling cubs. Without hesitation, the grizzly lunged at the first polar bear, huffing and snarling, driving it into the lagoon. Soon the second, third and fourth polar bears had joined it, leaving the food to the brown bear, which was about one-third their size. She just went in there and cleared them out, one after another and would not tolerate any bears being there with her cubs. The brown bears tend to be a lot more aggressive and rule the roost. They're not very tolerant of other bears around them, whereas the polar bears were amazingly tolerant.

POLAR BEAR WINS
Polar bears (1,100-1,300 lb) are generally larger than grizzly bears (300-700 lb) and are said to take off a human head with one swipe. Polar bears fight other polar bears more often than brown bears fight other brown bears. They have a ferocious disposition. A witness in a Northern Manitoba Landfill Site said that polar bears won't back off from anything, while a grizzly bear would run away. One person says the polar bear is the most carnivorous bear (true) and would be protected by its thick fur.

Looking at all the information above, it seems that the grizzly bear holds most of the advantages (strength, powerful jaws and claws etc) and would usually win a fight, especially if both bears were the same size. The polar bear would have the advantage in an Arctic environment, unless the fight took a lot of time - then the grizzly bear would have the advantage.

I hope this helps

All the best

Jonathan