An unusually intense summer of polar bear visits has put one of Svalbard’s key eider duck breeding areas under heavy pressure. In Kongsfjorden, researchers from the Norwegian Institute for Nature Research (NINA) recorded the highest number of bear visits ever documented at the site, raising concerns for the eider colony and for wildlife already threatened by a rapidly warming Arctic.
Between 4 June and 4 July, researchers recorded 30 days with bear visits to the ducks nesting in the fjord, meaning that on average one polar bear was present every day during the most vulnerable part of the eider nesting period.
“That is the highest number we have ever recorded,” said NINA researchers Sveinn Are Hanssen and Børge Moe after this year’s fieldwork on Svalbard.
Working with the Norwegian Polar Institute, the researchers monitor the eider population and document how it is affected by polar bears. Images from all but one of the eleven nest cameras showed bears feeding on the eggs. In the final case, the eider hen managed to hatch her eggs and leave the nest with her chicks before the bear arrived.
Field work conducted by the researcher later confirmed that very few eider hens succeeded in raising their young in Kongsfjorden this year.
As sea ice shrinks and breaks up earlier, polar bears lose access to the seal hunting grounds they normally depend on. On the pack ice, seals are their main prey because they provide the fat-rich food bears need to survive. With the ice cover shrinking year after year, the polar bears are forced onto land for extended periods of time and increasingly turn to other alternatives such as bird eggs. That makes nesting colonies a more frequent target at exactly the time when birds are most vulnerable.
Sea ice extent in June 2026 was already far below average, measured at 11.18 million square kilometers on 10 June, the fifth lowest on record for that date. The winter maximum was also exceptionally poor. The maximum extent of the winter sea ice reached its lowest-ever peak on 7 March, and March’s extent was the lowest on record for that month.
The research into eider colonies in Kongsfjorden has a long scientific history and has been carried out since the 1970s. NINA possess a data series on nesting eider ducks covering the period from 1981to 2026, giving scientists one of the region’s most valuable long-term records of Arctic bird ecology. Last year researchers from NINA also published a scientific paper showing that the thawing sea ice in turn isolates several islands from the mainland of Svalbard, thus offering better protection against predation by the Arctic fox Vulpes lagopus. The overall population of eider ducks however has been declining in recent years, in 2026showed a 28% reduction of eider ducks observed in the Kongsfjord research area.
Like several other arctic seabirds, eider ducks are also being affected directly by the warming environment itself. Studies have shown that cold-adapted Arctic birds are poorly equipped to cope with heat stress, meaning that nesting birds may face pressure both from predators and from the environment in which they breed. In the rapidly warming arctic, warmer summers can lead to increased heartrates, dehydration, overheating and increased energy consumption for the female breeding eiders, which regularly loose around 30-45% of their body weight while incubating their eggs.
Eiders are long-lived birds and can tolerate poor breeding success for some years. But repeated losses add up. Hanssen said that predation by polar bears has reduced breeding success in many seasons over the past decade, raising the question of whether the population is now beginning to decline.
“It is not unlikely that we are starting to see the effect of poor recruitment,” said Sebastien Descamps, seabird researcher at the Norwegian Polar Institute when asked about this year’s 28% decline in nesting birds.
For scientists, these results underline the value of long-term research in the Arctic, the fastest-warming region in the world. Only sustained monitoring can show whether years like this are isolated setbacks or part of a longer shift in the population development.