While we have "a flock of birds" or "a herd of elephants," there's no established term for a group of sirens.
Here are some creative options:
* A chorus of sirens (emphasizing their singing)
* A wail of sirens (referencing their sound)
* A lure of sirens (highlighting their enticing nature)
Ultimately, you can choose the most fitting term based on the context and the specific imagery you want to convey.