Skip to content

Active Monitoring in Bergen Detected H5N1 in Apparently Healthy Tufted Ducks

Male tufted duck swimming on calm water
Research · Disease, parasites & microbiology

Expanded surveillance during an H5N1 outbreak among waterfowl in the Bergen area found that apparently healthy tufted ducks (Aythya fuligula) could shed the virus without showing clinical signs. The finding is reported in a Norwegian Veterinary Institute status report published on 25 March 2026.

In early February, H5N1 was detected in six mute swans in Bergen and one in neighbouring Øygarden. The virus was also found in mallards, tufted ducks and a European herring gull. After sick swans were observed at a site in central Bergen, ornithologists from the Norwegian Institute for Nature Research helped initiate expanded active surveillance.

That surveillance showed that several apparently healthy birds, including tufted ducks, could shed H5N1 without obvious illness. The report notes that this was consistent with earlier findings from Rogaland and other European countries, where infected wild birds had also been detected without clear clinical signs.

The Bergen event occurred during a winter with very high HPAI activity among wild birds in Europe. In Norway, detections were scattered across several regions, and waterfowl were particularly affected. The report also cautions that the high number of February detections partly reflected unusually intensive sampling.

Sources and image credit

  1. Granstad, S., Ytrehus, B., Helberg, M., Åkerstedt, J., Gjerset, B., Bøe, C. A., Madslien, K., Meling, S., Fjermestad-Eie, B., Bergfeldt, A., Fjeldheim, I., Stålcrantz, J., & Tønnessen, R. (2026). Høypatogen aviær influensa – HPAI i Norge, Europa og globalt: Statusrapport for perioden 21. oktober 2025–20. mars 2026 (VI rapport 11/2026). Veterinærinstituttet.Official primary surveillance report published 25 March 2026. It documents the February Bergen-area H5N1 outbreak and expanded active surveillance showing that apparently healthy wild birds, including tufted ducks, could shed virus without clinical signs.

Image: gailhampshire — male tufted duck (Aythya fuligula) photographed at RSPB Titchwell, Norfolk, United Kingdom, 11 March 2017; representative species image, not a bird from the Bergen outbreak. Source: Wikimedia Commons. · CC BY 2.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

Disease, parasites & microbiology

SPECIES IN THIS STORY

Species in this story

Tufted Duck Aythya fuligula Explore species

Independent research and conservation news archive

Did you find this information useful?

Wildlife Vagabond is independently built and maintained. Voluntary support helps cover source verification, hosting and continued work on research and conservation news.

Support Wildlife Vagabond

The news archive will remain freely available.