Is mortality among wild birds caused by bird flu increasing again?
To the relief of many, reports of bird flu among wild birds in the Netherlands remained relatively low this past spring. Although the highly pathogenic H5N1 virus had not completely disappeared, increased mortality from this virus did not occur among the colony-breeding gulls and terns that had been severely affected in previous breeding seasons. However, since the end of May, we have observed some worrying developments locally. All the more reason to remain vigilant throughout the summer.
Recent reports
Various organizations are involved in monitoring bird flu among wild birds. Tests on live birds, which are caught and sampled for research, are mainly carried out by Erasmus MC, while tests on birds found dead are conducted by Wageningen Bioveterinary Research (WBVR). The involvement of a large number of people in the field—including bird ringers and researchers, land managers, and an extensive network of other vigilant observers—is indispensable. Through them, we receive timely signals about what is happening and where. In recent weeks, there have been several reports, especially from the province of Zeeland. For example, at the nature reserve Noordervroon near Westkapelle, at least 85 dead birds were found and removed by staff from Deltamilieu Projecten, mainly about one-year-old European Herring Gulls, but also Common Terns, a Pied Avocet, a Sandwich Tern, and a Black-headed Gull. Twelve birds were sampled, and all tested positive for the highly pathogenic H5N1 virus. Samples from dead European Herring Gulls and a dead Northern Gannet from other parts of the province of Zeeland (cities of Vlissingen, Domburg, Koudekerke) were also submitted and tested positive. In the province of North Holland, the same was true for a sampled live Common Buzzard. Furthermore, there are signs of increased mortality observed in the gull colony at the island Slijkplaat in the lake Haringvliet and in the city IJmuiden. These cases are still being tested. Every month, an overview of the test results of bird flu is published on our website.
Please keep reporting
Close to a year ago, we started systematically collecting more data on bird mortality through the LiveAtlas project. These bird counts are necessary to make more accurate statements about the course and scale of mortality peaks and their impact on populations. Participants in the LiveAtlas project are therefore encouraged to keep bird counting and reporting.
Dead birds can still be reported via our reporting form and through Sovon. There, you can also indicate whether the dead animal is available for post-mortem investigation. In that case, the DWHC will contact the reporter directly.
To arrange for the removal of dead animals, it is best to contact the land manager or the municipality.
Remain cautious
Bird flu is a zoonosis, which means the disease can potentially be transmitted from animal to human. It is therefore important to be cautious when approaching sick or dead wild birds and to follow hygiene measures. If you find a dead animal that you want to have collected for post-mortem investigation, it is important that the animal is double-bagged in plastic and is never touched with bare hands. A guide on how to handle wild animal with bird flu can be found on the website of the government: Guidelines for handling wild animals with avian influenza (in Dutch).
