How Scientists Discovered a New Polar Bear Population

When Dr. Kristin Laidre set out in search of the polar bears of southeast Greenland, she wasn’t expecting to uncover an entirely new subpopulation. In fact, if anything, she was anticipating seeing only a few scattered bears.

Tasked by the government of Greenland to conduct a population assessment of the bears on the island, Laidre assumed, as did everyone else, that the bears along Greenland’s east coast all belonged to one amorphous subpopulation. But the southeastern portion of the country remained a largely unknown quantity, largely due to its inaccessibility: Mountainous and glacier-strewn, it is also devoid of any settlements.

Laidre asked Indigenous hunters what they knew of the bears in the area, and “some people mentioned that there were some bears down there but that nobody hunted them or even really went there. But I started thinking that it was just a piece that we couldn't ignore; as part of the assessment, I had to at least confirm that it wasn't an important place for polar bears.”

A surprising find

She and her fellow researchers flew to the area and, to her surprise, “as we dipped into the area from the north, we saw that there were quite high densities of bears in the fjords.”

The area in which Laidre, a professor with the University of Washington and a researcher affiliated the Greenland Institute of Natural Resources, saw those bears was an unusual one for polar bears: in deep fjords, hemmed in by mountains, with the Greenland ice sheet at one end and the North Atlantic Ocean at the other. Further visits—which, because of the logistical challenges of operating in the area, took years to complete—would reveal even more surprising details. Most notably, this group of polar bears spent the bulk of its time living without sea ice, as a strong southward-flowing current carries ice floes past the entrance of the fjords in which the bears live.

“The offshore area is very poor polar bear habitat,” says Laidre. “It’s made up of very small ice floes moving very rapidly. It's like a conveyor belt of lousy habitat flowing along the outside of those fjords.” Instead, the bears were hunting seals from glacier ice that had been calved from the ice sheet.

Still more surprises awaited. Laidre and colleagues were able to place radio collars on some of the bears in the population. Their tracked movements showed that the bears were highly localized. They stayed among the fjords and didn’t interact with bears farther north at all, although some would travel from fjord to fjord.

“It's quite amazing,” Laidre explains. “They climb up along the sides of the glacier, they climb up mountains, and you can track them in the helicopter as they climb higher and higher and higher, and then they will literally slide down into the next fjord. And they do make some trips out onto the pack ice. It’s a risky venture, because it's moving so fast. But we see that they take these trips out onto the pack ice, then they're moving very rapidly south, and they'll jump off and walk on land back to their home fjord.”

Genetically isolated

When Laidre and colleagues fitted radio collars, they also took some small biopsies for genetic analysis, and that revealed the biggest surprise of all.

“I remember the day I got the email from the genetics lab,” Laidre recalls. “And even the geneticists were blown away by what they found. They had been working on circumpolar polar bear genetics, and they said that these are the most genetically isolated polar bears on the planet.”

Not only did the bears of southeast Greenland not mix with bears farther north, but the DNA evidence also suggested that they hadn’t done so for at least 200 years.

There is not yet an assessment of the population’s size, but Laidre provisionally estimates there are probably between 200 and 400. The notion that these polar bears have been isolated from other bears for centuries while apparently thriving without sea ice might seem cause for optimism for the species’ ability to survive in a warming world. But Laidre cautions that, while the discovery is certainly interesting, it does not by any stretch of the imagination mean that polar bears don’t have to worry about retreating sea ice.

“This is a really unique habitat,” she points out. “Glacial habitats are not found in all of the Arctic, or in most of the polar bears’ range. So no, polar bears aren’t going to be saved by glacial ice. And besides, glacial ice is itself in retreat. What it can possibly tell us, however, is something about where polar bears might persist as a species, the pockets of habitats where polar bears could survive for longer periods when we have very little ice in the Arctic. And I do think that environments like this are one of those places that might help the species along. But no, it’s not going to save polar bears. We’re still going to see a lot of the same predicted declines around the Arctic, especially in all the places with no glacial ice.”

In 2022, Laidre and colleagues published a paper in Science, in which they argued that the bears’ genetic uniqueness and physical isolation qualified them as the 20th subpopulation of polar bears in the world—a position rubber-stamped by the Polar Bear Specialist Group, the world’s primary scientific body on the species, in June 2024.

For Laidre, the discovery is an example of how the natural world never ceases to amaze and reveal new surprises.

“It's one of the amazing parts of being a scientist,” she says. “You can really learn amazing, cool new things, and you just have to have an open mind and be willing to explore new directions. And because of that, we’ve learned something new and really interesting that’s going to teach us more about polar bears and their conservation.”