Polar Bear vs Grizzly Bear: Size, Diet and Hybrids

Key differences at a glance

The polar bear (Ursus maritimus) and the grizzly bear are separate species. “Grizzly” is the common name for inland North American populations of the brown bear (Ursus arctos), the same species that lives in Europe and Asia. For more on the name, see is a grizzly a brown bear?

The quickest ways to tell them apart are color, shape and where you see them. A polar bear is white or cream, with a long neck and a narrow head, and lives on the sea ice. A grizzly is brown, blond or nearly black, with a big shoulder hump and a broad face, and lives mainly on land.

Size: which bear is bigger?

The polar bear is the larger species and the largest land carnivore on Earth. Male polar bears are usually 2–2.5 m (6.6–8.2 ft) long, while inland grizzly males are smaller, often around 1.8–2.4 m (6–8 ft) long.

The picture changes if you include coastal brown bears. On the Kodiak Archipelago and Alaska Peninsula, where salmon are plentiful, large male brown bears can reach about 480–635 kg (1,050–1,400 lb) in autumn, which overlaps with polar bears. Full figures are in how big are polar bears?

Body shape, fur and claws

Polar bears look longer and more streamlined. They have a long neck, a fairly narrow head with a straight or slightly Roman-nosed profile, and small ears. The grizzly is stockier, with a muscular hump above the shoulders that powers digging, a broad head with a dished (concave) face and rounder ears.

The coats are very different. Polar bear guard hairs are transparent and hollow and look white or cream, over black skin. Grizzlies range from blond to dark brown, and many have pale tips to the hairs that give a grizzled, silvery look, the origin of their name. Grizzlies also have long, fairly straight front claws, often 5–10 cm (2–4 in), made for digging roots and burrowing rodents. Polar bear claws are shorter, thicker and more curved, made for gripping ice and holding seals.

Diet: seals vs almost everything

The polar bear is the most carnivorous bear. It eats mainly ringed and bearded seals, feeding largely on their fat-rich blubber, and its cheek teeth are smaller and more jagged than those of other bears, suited to meat rather than plants.

The grizzly is a true omnivore. In much of its range, most of its diet is plant matter: grasses, sedges, roots, berries and nuts. It also eats insects such as army cutworm moths, ground squirrels, salmon, carrion and, in some areas, young elk, moose or caribou. Where grizzlies reach the Arctic coast, they also scavenge on stranded whales and sometimes take seals, which brings them into contact with polar bears.

Habitat and where they meet

Polar bears live around the Arctic Ocean, mostly on sea ice over continental shelves, in Canada, Alaska, Greenland, Svalbard and Russia. Grizzlies live in western North America, from Alaska and northern Canada south to the Rocky Mountains of Wyoming and Montana, in forests, mountain meadows and tundra.

The two ranges meet along the Arctic coast of Alaska’s North Slope, in the western Canadian Arctic around the Mackenzie Delta and the islands of Banks and Victoria, and in western Hudson Bay. In recent decades grizzlies have been seen farther north and more often on the coast. Observations at whale bone piles near Kaktovik, Alaska, found that grizzlies usually won disputes over food, even though polar bears were generally larger.

Behavior and winter

Grizzlies spend winter in dens, typically for four to seven months depending on the climate, living on body fat. Polar bears do not den in this way, except for pregnant females, which dig snow dens where they give birth and nurse their cubs. Other polar bears stay active all winter, hunting seals on the ice.

Both species are mostly solitary, apart from mothers with cubs, and both can run at around 40–48 km/h (25–30 mph) over short distances. Polar bears are far stronger swimmers and are often classed as marine mammals.

Pizzly and grolar bears: polar–grizzly hybrids

Because the two species are so closely related, they can produce fertile offspring. Hybrids had been born in zoos before, but the first wild hybrid was confirmed by DNA in 2006, from a bear killed on Banks Island in the Northwest Territories. It had creamy fur with brown patches, long claws, a small hump and a dished face. Its mother was a polar bear and its father a grizzly.

By 2017, eight wild hybrids had been confirmed, all in the Canadian Arctic and all descended from a single female polar bear that mated with two grizzly males; some were second-generation offspring. Names for these bears include pizzly, grolar and nanulak, from the Inuit words for polar bear and grizzly. Hybrids remain rare, and scientists do not expect them to replace either species.

Genetic studies show that polar bears and brown bears have exchanged genes many times in the past. Brown bears on Alaska’s Admiralty, Baranof and Chichagof (ABC) Islands, for example, carry a noticeable share of polar bear DNA from ancient mixing.

Conservation status

The polar bear is listed as Vulnerable on the IUCN Red List (2015) because of sea ice loss, and as threatened under the US Endangered Species Act. The brown bear as a whole is Least Concern, with roughly 200,000 animals worldwide, although grizzlies in the lower 48 US states are listed as threatened. For another comparison, see grizzly bear vs black bear.