This question goes to the very heart of this intriguing poem. Of course, the poem represents an enactment of the sirens' song, which in Greek mythology was so compelling that anyone who heard it would be driven to their deaths by their desire to approach the sirens.
Certainly the speaker of the poem makes no attempt to hide the fate awaiting her listener - there are lots of examples of foreshadowing, with "leap overboard in squadrons", "beached skulls" and "anyone who has heard it is dead". Yet crucially, and fatally, the speaker of the poem is so convincing in presenting the image of both the "irresistible" attractions of the song but also painting a pitiful picture of herself that makes the reader feel sorry for her. There is the attraction of knowing the "secret", and balanced with that the sorrowful cries of a character who wants to "get... out of this bird suit", who doesn't enjoy her role, "squatting on this island". This two attractions of selfishness to possess the secret and also the idea of rescuing the speaker culminate when the speaker says:
I will tell the secret to you,
to you, only to you.
come closer. This song
is a cry for help: Help me!
Only you, only you can,
you are unique
Of course, after this, the reader realises that they too have been tricked like so many before them. Interestingly however, the irony of poem goes a lot deeper, as the last 3 lines suggests that the speaker is actually unhappy in her position and is bored with the ease of her success. Was she actually sincere in what she said and really wanting an escape? This poem raises interesting questions about the theme of seduction and how such a role can trap the seducer just as much as the one who is seduced.