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Antibodies Against Avian Influenza Detected in Polar Bears in Greenland

Voksen isbjørn med to unger ved iskanten, speilet i rolig vann.
Polar bears live on sea ice, but are increasingly forced to move onto land as the ice melts. There, they face a risk of influenza transmission from birds. The photograph was taken by researchers near Ittoqqortoormiit in eastern Greenland.

For the first time, antibodies against avian influenza have been detected in polar bears in Greenland. Researchers still know little about how lethal the virus is, but believe increased surveillance could provide early warnings of its spread.

Linn Ophaug
Linn Ophaug Science journalist
Published Modified

Between 2016 and 2025, researchers, in collaboration with local hunters, collected blood samples from polar bears in East Greenland, near the town of Ittoqqortoormiit.

In the study, published in the journal Emerging Infectious Diseases, researchers detected antibodies against avian influenza for the first time in 2024.

The following year, blood samples from nearly half of the animals tested came back positive, including for highly pathogenic avian influenxa of the H5 type.

"What is unique about this study is that we can see the development over time, going back to 2016. Until 2024, we found nothing. Changes have occurred in a short period of time," said wildlife researcher and lead author of the study, Kayla J. Buhler, in a press release.

Facts about the study:

  • The researchers examined 109 blood samples from polar bears culled near Ittoqqortoormiit between 2016 and 2025.

  • The samples were collected in collaboration with local hunters engaged in traditional hunting.

  • No antibodies against influenza A were detected before 2024.

  • In 2024, 3 of 14 bears (21 percent) had antibodies against influenza A. In 2025, 6 of 14 (43 per cent) had such antibodies.

  • The researchers identified antibodies indicating that some of the animals had been exposed to highly pathogenic avian influenza H5, clade 2.3.4.4b.

  • The polar bears appeared healthy when they were culled, and the hunters reported no signs of illness. This suggests that polar bears can survive infection.

  • The researchers behind the study are from universities in the United States, Canada, Denmark and Norway.

Source: University of Inland Norway

Greater risk of infection

Person med snødekt lue og ansiktsmaske i et vinterlandskap
Kayla J. Buhler, a wildlife researcher at University of Inland Norway, studies the cold Arctic and led the international study in Greenland.

Polar bears in Greenland live on sea ice, which they use as a platform for hunting seals. Life on the ice has likely meant that they have been less exposed to infectious agents that are common on land.

Climate change, however, with rising temperatures and shrinking sea ice, has led polar bears to spend more time on land.

"­There, they must adapt to new conditions and may increasingly eat birds and bird eggs to avoid starving. ­This can make them more vulnerable to infection. They can also contract the virus by eating mammals that carry it," Buhler explained.

At the same time, the avian influenza virus has evolved into new variants capable of infecting mammals, and polar bears may be particularly susceptible.

Dead polar bears infected with the virus have previously been found in both Alaska and Svalbard, but researchers currently know little about the mortality rate among those infected.

In Greenland in particular, with its vast distances and limited human activity, it is especially difficult to gain an overview of dead polar bears.

"The positive result of our study is that these polar bears survived and appeared healthy. They had probably been infected several months earlier."

Smilende kvinne i rutete skjorte ved en innsjø under overskyet himmel.
Kayla J. Buhler by the Glomma river, at the University of Inland Norway's Evenstad campus. Researchers from Canada, the United States and Denmark also contributed to the study.

Need to monitor developments

Greenland serves as an international hub for birds, where the migration routes of birds from both Europe and the Americas converge, making the region particularly interesting to monitor.

Bird migration takes place in summer and autumn, while the blood samples were collected during the hunting season from January to May. According to the report, the bears were likely infected during the bird migration season the year before they were caught in 2024.

Buhler believes the study underlines the need to monitor the development of these influenza variants in polar bears and other mammals in Greenland.

"Greenland is a unique place to study. This is where the migration routes of birds along the eastern Atlantic coast and the North American Atlantic coast meet. Increased monitoring in the area can therefore provide early warnings about the spread of highly pathogenic avian influenza, Buhler said.

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