norma-bara:

The Alkonost is, according to Russian folklore, a creature with the body of a bird but the head of a beautiful woman. It makes sounds that are amazingly beautiful, and those who hear these sounds forget everything they know and want nothing more ever again, rather like the sirens of Greek myth. The alkonost lays her eggs on a beach and then rolls them into the sea. When the alkonost’s eggs hatch, a thunderstorm sets in and the sea becomes so rough that it is untravelable. The name of the alkonost came from a Greek demigoddess whose name was Alcyone. In Greek mythology, Alcyone was transformed by the gods into a kingfisher.