Svalbard’s polar bears maintaining body condition despite sea ice loss

A new long-term study of Svalbard’s polar bears finds that adult bears have largely maintained body condition between 1995 and 2019, despite the region’s rapid loss of sea ice. Published today in Scientific Reports, the research is led by the Norwegian Polar Institute, alongside the University of Alberta, University of Oslo, and Highland Statistics. While this finding is cautiously positive, scientists stress it does not mean polar bears are safe from climate change. The study highlights how climate impacts are highly dependent on local conditions, underscoring the need for long-term research and monitoring. While biodiversity hotspots offer hope, continued sea ice loss will ultimately threaten polar bear survival in Svalbard and across the Arctic.

To learn more about this exciting new research, we talked with report authors Dr. Jon Aars, lead author and Senior Researcher at Norwegian Polar Institute, and Dr. Andrew Derocher, report co-author and Professor of Biological Sciences at the University of Alberta, along with Dr. John Whiteman, Polar Bears International’s Chief Research Scientist and Associate Professor of Biology at Old Dominion University. 

What does this new research tell us about polar bears?

Dr. Andrew Derocher: This paper highlights how different polar bear populations can be from one another, using Svalbard as an example during more than two decades of rapid sea ice loss. Bears in this region appear to be experiencing short-term buffering to climate impacts because they hunt in areas with diverse and new types of prey, which helps explain why adult body condition has remained stable so far despite rapid sea ice loss. But this resilience is temporary, and long-term monitoring remains essential for understanding when ecological thresholds will be crossed throughout the Arctic.

Why do you think this is happening?

Dr. John Whiteman: Several factors unique to Svalbard could be helping the bears; they have a diverse prey base, giving them choices as conditions change, and allowing some of them to maintain remarkably small home ranges, reducing their energetic needs. These bears may also still be recovering from extremely high levels of harvest prior to limitations enacted in 1973. Fully understanding these drivers requires continued monitoring, which emphasizes the importance of collecting long-term datasets. 

Are these polar bears adapting?

Dr. Jon Aars: No, it’s not what you call a genetic adaptation, because the timescale is too short. But they’re making the best of the situation; they’ve always been very opportunistic and will eat a variety of foods. It’s not like they suddenly are doing things differently, for example, you need to try a few times before you learn how to catch a reindeer — we’ve been seeing bears hunt reindeer in Svalbard for a long time. Another benefit is that Svalbard doesn’t have other predators that compete with polar bears for terrestrial food — there aren’t brown bears, wolves, wolverines, or foxes. 

Dr. Andrew Derocher: In the context of hunting reindeer, it's not what I'd call adaptability or adaptation because that implies an evolutionary process and selection for this behaviour. I'd call this more behavioural plasticity — the bears can hunt reindeer, which they’ve been doing in Svalbard since the 90s.  Polar bears evolved to hunt seals out on the sea ice: they will, however, try to kill other prey and sometimes do. It’s because polar bears have access to their primary, energy-rich diet in the form of ringed seals (small meal deal) and bearded seals (the big meal deal) that they can eat reindeer, walrus, and harbour seals — but without the ice, they lose their primary food source.  It's the lucky or skilled few bears that get this prey, and it's a benefit for them, but lots of other bears will be in areas with few or no reindeer.

What’s unique about the Barents Sea region? 

Dr. Andrew Derocher: You could see very rapid changes in this population, because this is the area of the Arctic where we're losing sea ice faster than anywhere else. But the big buffer for this population is that it's a very productive ecosystem. We've got a lot of water coming in from the North Atlantic, bringing a lot of nutrients. There's a massively wide continental shelf area, which is where polar bears like to be — these shallow waters are where the ecosystem is most productive. And there are more seals, which means the bears do better. As the study shows, we have declining sea ice cover, but so far, the decline hasn't happened over the whole continental shelf. So there are still areas of very high productivity in this area that the bears can exploit. So in many ways, it really shows us that polar bear populations are not all created equally when it comes to the effects of climate change. We expect, over the longer term, that this population, like many of the others in the southern parts of the range, will decline and probably blink out at some point if climate change continues.

Dr. John Whiteman: Svalbard is home to both pelagic polar bears, which drift with sea ice over long distances, and local bears, which remain on land during ice-free periods and are the subset primarily represented in this research data due to their accessibility. It's a striking difference between these two groups: local bears can have a whole range that is 1/30 the size of pelagic bears, so they might have a home range of several thousand square kilometers, whereas the pelagic bears might have a home range of over 100,000km².

What does this tell us about polar bears across the Arctic?

Dr. Jon Aars: Svalbard is one of those places where we have a lot of data, and it shows the importance of studying polar bears with long-term data across the Arctic. You have to be careful not to extrapolate the findings — you can't just study two places and say, if you lose this much sea ice here, polar bears will do this there, etc. Polar bear research is complex, and all polar bear populations are different. It’s not black and white, and what you find in one place doesn't always tell you what will happen in other places. 

Dr. John Whiteman: There are 20 unique polar bear subpopulations, each shaped by local geography, food availability, and sea ice dynamics. This research shows how the short-term impact of sea ice loss on polar bears is surprisingly variable, and tells us a lot about the influence of local conditions. But the long-term, big picture consequences of ice loss remain dire. All polar bears need sea ice, and climate change remains the key threat to this species.