H5N1 Avian Influenza Outbreak Caused Massive Mortality of Chicks of Sandwich Tern Thalasseus sandvicensis in the Lagoon of Venice

Highly pathogenic avian influenza has emerged as a global menace over the past decades, posing a dramatic threat to birds worldwide, and its spread is of great concern to both conservationists and health authorities. In the 2022 breeding season, the Sandwich Tern Thalasseus sandvicensis was affected by a northwestern Europe-wide pandemic of the highly pathogenic avian influenza A (strain H5N1). This note reports on the occurrence of avian influenza in Sandwich Terns breeding in the Lagoon of Venice (Italy) in 2023 where the outbreak exterminated all chicks, but spared the adults.