Researchers have identified a previously unknown population of polar bears living in isolation Southeast Greenland. The bears hunt for seals on fjords, or freshwater ice shelves, instead of on rapidly receding sea ice like other polar bear species.
A new report in the journal Science describes the population, which now brings the total number of known polar bear groups from 19 to 20. Scientists were aware that some polar bears could be in this area based on historical records and knowledge from Indigenous communities in the Arctic, and they were finally able to confirm that this is a separate population.
“Polar bears in SE Greenland are the most genetically isolated polar bears on the planet. They are distinct from all other 19 polar bear subpopulations in the Arctic and more diverged from neighbouring subpopulations than any other pair,” Kristin Laidre, University of Washington polar scientist and lead author of the study, said in an email to Earther. “They have been separate for a few hundred years, and likely always have been a small population.”
The scientists worked for years to establish research posts out in Greenland, collar the bears, and monitor them to confirm their adaptability and isolation. Laidre said this new group was tracked from 2015 to 2021.
Elizabeth Peacock, an assistant professor at the Emory University School of Medicine and a polar bear expert, wrote a Perspective article to accompany to Laidre’s research in the journal Science. She explained that some posts online have hinted that this isolated bear group could be a “thriving” population because they have found a new way to hunt. But Peacock she’s not confident that’s the case.
“Plasticity generally refers to an individual that has the ability to, you know, to use different behaviours… so, ‘I can figure out how to kill a walrus or I can figure out how to catch fish’,” she said. “Natural selection is about adapting over time… that assumes that polar bears have enough time to change what they’re doing to respond to natural selection.”
Unfortunately, the effects of climate change are happening faster than many polar bears can reproduce.
In her article, Peacock pointed to other known polar bear populations that have shown signs of plasticity, such as nesting farther inland away from depleting sea ice or hunting for different types of prey when their usual seal diet isn’t as abundant. There are questions as to whether glacier hunting will continue to be possible in the future, as ice melts in both poles. Polar bear generations are about 10 years long, but climate change is affecting ice at a rate much faster than that. Researchers are worried that this new behaviour may not be passed down, because the climate crisis is quickly depleting ice in the Arctic.
“We have NO IDEA if they are thriving. We know nothing about whether the population is stable or in trouble. This will require more research,” Laidre said in an email. To actually determine how this population is faring in the face of climate change, scientists will have to study the survival of adult female polar bears by marking them and studying them over three or four years.
“Glacier ice may help small numbers of polar bears survive for longer periods under climate warming, and may be important to the species persistence (meaning preventing extinction), but it is not available for the vast majority of polar bears,” she said. “Future monitoring these bears can perhaps tell us a bit more about the future for the species.”