A flying siren is a rare singing bird of moderate beauty and size. However, it has a human voice. Not knowing the meaning of the lyrics or words he/she hears. It simply imitates the human phrases it hears and puts them in singing form. Like a parrot, only more accurate, less repetitive and always in singing form.
Flying Siren have been known to lure people to deep into forests, these people thinking they were following someone's voice.