Charakterystyka ornitologiczna stada labedzi niemych z pierwszego ogniska HPAI H5N1 w Polsce

The aim of the study was to determine the biometrical features, sex and age structure of H5N1 positive mute swans living on the Vistula River (in Toruñ city). The flock consisted of 68 male and 44 female birds. More than 70% of the swans were adult. There were no differences between HPAI positive and negative birds in body weight, size and condition. Thus, the virus shading was independent of the bird’s sex and condition. The mean body weight of Toruń’s mute swans was comparative to the weight of birds from other flocks in the winter season. The flock consisted of birds migrating along the Vistula River and Notec Valleys.