Common Tern (Sterna hirundo)
A migratory bird of the family of terns, with a slim body, narrow wings and quite a long, deeply forked tail. Both males and females are white-gray with a black crown of the head. It is a social species that usually nests in colonies in river valleys, especially where there are sandy or gravelly islands and shores. It feeds mostly on small fish and insects, crustaceans and molluscs associated with the aquatic habitat. It catches fish by diving from the air into the water several meters deep. It lays eggs in hollows in the sand which are lined with a few stones or shells. Humans and predators can be a significant threat to these birds during the breeding season because when the birds are scared the eggs remain too long without care, which exposes them to overheating in hot sand. Hatching sites may also be damaged by floods, or sudden changes in the water level.