In April and May 2023, dozens of dead black-headed gulls (Chroicocephalus ridibundus) were found in the province of Flevoland. Wageningen Bioveterinary Research (WBVR) studied thirteen of these black-headed gulls. In all these gulls, highly pathogenic H5N1 bird flu virus has been found.
As of January 2023, dead wild birds were found in several municipalities and examined by WBVR for the presence of bird flu viruses. Until mid-May 2023, 277 wild birds have been studied, of which 250 were positive for highly pathogenic H5N1 bird flu virus.
In 27 of the 33 bird species studied, highly pathogenic H5N1 bird flu virus was found, but remarkable is the large number of positive gulls. The virus was found in 200 black-headed gulls, six herring gulls and ten birds from four other gull species.
