Spread across the Arctic, nineteen genetically distinct subgroups of polar bears had been mapped to date, each group with its own more or less defined habitat: from Svalbard and Franz Josef Land, via the Siberian coast around the Arctic, to Canada and western Greenland. . Polar bears on the sparsely populated eastern coast of Greenland (even by Arctic standards) have thus far been seen as one collective group. Based on genome research, RNA samples and field observations, the researchers now conclude that the East Greenland bears form two separate groups. The animals on the Southeast coast live very isolated and have little contact with their neighbor bears above the 64th parallel.
The researchers offer two explanations for the isolation of the new subgroup: hunting and geography. On both sides of the habitat, which stretches for about 600 kilometers of fjord coast, are Inuit settlements where polar bear hunting is allowed. Indigenous residents of Greenland are allowed to shoot a limited number of polar bears for their own use every year.
Katabatic winds
Due to the characteristics of the landscape, the bears remain in place. To the north and south of the habitat are mountains over 2,000 meters high; on the north side, there are also so-called katabatic winds, gusts from the ice sheet that can increase to speeds of 300 kilometers per hour due to temperature difference and gravity.
The strong north-south sea current off the coast is also a geographic limitation. Because of that current, the polar bears hardly venture outside the fjords. Animals that unexpectedly end up at sea, float south on the current. After an average of 200 kilometers they clamber ashore again, after which they walk back to their territory.
The habitat in Southeast Greenland, the researchers say, resembles predictions for the entire Arctic by the year 2100. Little sea ice forms in the fjords during the winter, and the ice that forms melts away earlier. Polar bears, on the other hand, hunt from sea ice, but here they adapt their behavior and hunt from glaciers that open into the seawater.
Biologist and polar researcher Maarten Loonen calls the link with climate change ‘a little sought after’. “But it’s fantastic how they’ve shown that these polar bears form their own twentieth subgroup.”
Opportunistic Hunters
Loonen, affiliated with the Arctic Center of the University of Groningen and not involved in the polar bear study himself, responds by telephone from Ny-Ålesund on Spitsbergen, where he has been conducting research for 33 years. It does not surprise him that the bears are able to survive in an area with little sea ice. Polar bears are opportunistic hunters. We’ve got a polar bear here that has just fed the eggs of the geese we’re researching.’
Loonen points out another important point in polar bear behavioral research, not just here, but in all studies: The shape of their heads and necks prevents male bears from wearing a collar. This means that research with a GPS transmitter is only done on females. ‘A male polar bear has a kind of torpedo shape, with no visible neck, which would cause a collar with a GPS tracker to slide off its head. What we know about polar bears, we usually know about females.’