Abstract
Avian influenza is one of the most dangerous known diseases of poultry. Due to the complete extinction of the entire poultry population, the spread of influenza in poultry farms usually leads to significant economic losses throughout the world. Migratory birds, especially waterfowl, are a natural reservoir of the avian influenza virus. During migration, they exchange with different strains of the virus, causing antigenic drift and antigenic migration, which leads to the emergence of highly pathogenic avian influenza viruses. Their seasonal migration plays an important role in the formation of the genetic structure of the viral population. This requires constant observation of the evolution of the avian influenza virus and regular monitoring in various places to prevent new outbreaks of epizootic and epidemic diseases.