A polar bear's head glides past at water level, the camera bobbing beside it in the cold Arctic sea. Polar Bears: The Quest for Sea Ice, released by GoPro on 21 June 2014, follows a family of polar bears as they swim across open water in search of ice. It was shot entirely on GoPro HERO3+ cameras for Arctic Bear Productions, the company of Arctic wildlife filmmaker Adam Ravetch, co-director of Disney's Arctic Tale.
Watch the polar bear GoPro film
The film puts the viewer in the water with the bears: heads and backs breaking the surface, paws pulling through the clear green sea and, now and then, the edge of the ice they are heading for.
Polar bears are marine mammals
The scientific name, Ursus maritimus, means "sea bear", and polar bears are officially classed as marine mammals because they depend on the sea for food. Adult males weigh 300 to 800 kg, which makes them the largest land carnivores on Earth, while females are about half that size.
They are strong, patient swimmers. Broad front paws work as paddles, the hind legs steer, and a thick layer of fat keeps them warm and buoyant. They swim at up to about 6 km/h. In a study of bears in Alaska's Beaufort Sea, long-distance swims averaged 154 km and lasted 3.4 days, and USGS tracking shows bears keep going without stopping to rest. Their fur looks white, but the guard hairs are actually transparent, and the skin underneath is black to absorb heat.
Why sea ice matters to polar bears
Polar bears eat almost nothing but seals, above all ringed seals, along with bearded seals. They catch them from the ice: a bear waits beside a breathing hole or at the edge of a floe, sometimes for hours, then hooks the seal out with its claws as it surfaces. In open water a seal is far too fast for a bear, so without ice the bears cannot hunt.
The ice is also where they travel, mate and, in some regions, den. Pregnant females dig maternity dens in October or November, give birth in December or January and emerge with their cubs in March or April. In Alaska's Southern Beaufort Sea, thinner and more broken ice over the last three decades has pushed many females to den on land.
Polar bear populations and a changing Arctic
Scientists recognise 19 polar bear subpopulations around the Arctic, in Canada, the United States (Alaska), Greenland, Norway and Russia. The IUCN estimates a total of 22,000 to 31,000 bears and lists the species as Vulnerable, and the United States has listed it as threatened under the Endangered Species Act since 2008, because of the loss of sea ice.
As summer ice retreats earlier and returns later, bears must fast longer on land or swim farther between floes. The USGS Alaska Science Center has studied the Chukchi Sea and Southern Beaufort Sea populations since 1985, using satellite collars to follow exactly these journeys.
Related reading
- Polar Bears and Sea Ice: The Context Behind a Swimming Film
- Churchill’s Tundra Lodge: A Mobile Base for Polar Bear Watching
- Churchill in Google’s Panoramic Imagery: Looking around the Tundra
- Andrew Manske’s Polar Bear Mother and Cubs in Manitoba
- Gerda and Her Cub: Vera Salnitskaya’s Polar Bear Photographs
- Drew Hamilton’s McNeil River Bear Encounter
Sources
- GoPro: Polar Bears – The Quest for Sea Ice (YouTube)
- Polar bear research – USGS Alaska Science Center
- Polar bear – Wikipedia
- Photos and film: GoPro / Arctic Bear Productions.
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