Polar Bears and Grizzly Bears

By Tala

You've seen those pictures of polar bears floating on single blocks of ice, right? And you’ve heard of grizzly bear attacks on the news I assume? Well these two species of bear aren’t as different as you thought. Polar bears and grizzly bears have a lot in common, but also a lot of differences. They are large and can be quite fierce. However, their fur looks noticeably different from each other, as they live in different climates. While both are large, the polar bear is larger, weighing up to 1,000 kilograms, which is as heavy as 2 grand pianos. The grizzly bear, however, can only weigh up to 700 kilograms. There are also many other differences and similarities between polar bears and grizzly bears in terms of taxonomy, habitat, behaviour, and diet, that will be discussed in this essay.

The taxonomy of the grizzly bear and the polar bear are pretty similar. Both have the same kingdom, phylum, class, order, family, and genus. The only difference is that the grizzly bear is of the Ursus arctos Linnaeus species. The polar bear, however, is of the Ursus maritimus Phipps species. It’s not too surprising that they have a lot of similarities in taxonomy, since they are both bears. The fact that they live in different habitats could be a factor that plays in the difference between species. The polar bear lives in the ice cold Arctic Circle region, while grizzly bears tend to live in western North America. While both are cold, the polar bear’s climate is significantly colder.

Grizzly bears and polar bears also have similarities in behavior. For example, both show aggression or agitation by lowering their head. However, polar bears are active year round, while grizzly bears hibernate for 3 to 6 months. Both species have to charge up in the summertime, though, with occasional naps. That being said, grizzly bears make dens in certain places during winter. Some places include rock crevices, hollow trees or logs, under the root mass of trees, and even up high a tree in warmer climates. Polar bears, on the other hand, sleep in shallow pits they dig up in the snow during winter, and in summer they curl up on the sea ice. Landlocked polar bears tend to sleep in the tundra or dig sleeping pits in the sand or gravel ridges on the shore.

The difference between the diets of the grizzly bear and the polar bears are like day and night. Grizzly bears have an omnivorous diet, whereas polar bears have a carnivorous diet. Grizzly bear diets consist of less than 10% meat or fish in Idaho and Washington, a lot of the meat coming from deers and elk killed in winter. In places where there is less animal matter, important parts of the grizzly bear’s vegan-like diet include grasses, bulbs, roots, tubers, and fungi. In the springtime, grizzly bears usually eat easily digestible succulent plants that are high in protein, which can usually be found near wetlands. Their summer diet consists of thistle, mushrooms, roots, cow parsnip, spawning fish, wild berries, and insects, while their autumn diet consists of plants, ants, and most importantly, berries. Polar bears, meanwhile, mainly eat seals. Most of the time, polar bears will eat ringed seals, but they can also eat bearded seals. Seal pups are also quite an important food source for polar bears. They also eat walruses and whale carcasses.

The taxonomy, habitat, behavior, and diet of polar bears and grizzly bears aren’t too different from one another, nor are they alike. Whilst being practically twins in taxonomy from kingdom to genus, the only thing that separates them is their species. The polar bear lives in much colder climates, after all. In turn, this led to the polar bear and the grizzly bear being physically different, and growing up to have different behaviours. One difference being that grizzly bears hibernate while polar bears don’t. To conserve energy for hibernation, the grizzly bear has a certain diet. Grizzly bears have omnivorous diets, and eat mostly plants, roots, tubers, berries, and fungi. Polar bears, however, have carnivorous diets, which contain ringed seals, bearded seals, seal pups, walruses, and whale carcasses. While they are different, they are both still bears, so it’s no surprise that they have certain things in common.

Works Cited

“Behavior.” Polar Bears International, https://polarbearsinternational.org/polar-bears-changing-arctic/polar-bear-facts/behavior/. “Grizzly Biology & Behavior.” Western Wildlife Outreach, 25 Oct. 2015, http://westernwildlife.org/grizzly-bear-outreach-project/biology-behavior/. “Integrated Taxonomic Information System - Report.” ITIS, https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=180542#null. “Integrated Taxonomic Information System - Report.” ITIS, https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=202385#null. Jensen, Elle Di. “When Are Grizzly Bears Awake & When Do They Sleep?” Pets on Mom.com, 19 Nov. 2020, https://animals.mom.com/grizzly-bears-awake-sleep-1603.html. “Polar Bear.” National Wildlife Federation, https://www.nwf.org/Educational-Resources/Wildlife-Guide/Mammals/Polar-Bear. “When Bears Prepare for Winter (U.S. National Park Service).” National Parks Service, U.S. Department of the Interior, https://www.nps.gov/articles/bears-winter.htm#:~:text=Bears%20make%20their%20dens%20in%20hollow%20trees%20or,they%20stored%20in%20summer%20and%20fall%20as%20energy.