Sirens of Equis are die hard territorial creatures, pods often controlling miles of coastline or an island chain to themselves with larger areas held by big pods of thirty members if fruitful and out of harms way. Though usually a pack is often sought after by hungry predators of all kinds or even poaching by pirates for their rubies, so this drives sirens to be very competitive when a merpony, mermaid, or even a kelpie with a voice they find too talented. If such an unfortunate individual ever wondered into siren territory and sang even long enough for them to be detected, they are immediately surrounded by sirons who keep them from escaping while the Matriarch and her sirens arrive and initiate a Contest of the Songs.
Rarely do offenders or intruders prove themselves to be rivals of a siren's illustrious voice, but those who do escape unharmed and with blessings so long as they promise to never come back. The ones who do not pass the test are swarmed by the sirens of the pod and ritualistically eaten with the sirons present should the interloper prove to be too resourceful and manage to escape the initial attack. Sirens eat their contenders as an act to absorb their being, though the fact of the matter is, they simply consume them to be rid of a threat to their songs to their prey. A mermaid who'd drown a sailor, a Kelpie who'd ruin a village just to send water spirits back into the ocean, or a simple merpony who'd spill the beans on the siren's intent with their visits to harbors or coastal towns are a threat to a pod's well being and have to be handled in kind.
For this unfortunate mermare, she just wanted to sing to a cruise ship coming into a string of islands as part of its voyage. What she did not know was that she ventured into the wrong neighborhood and she'd soon find how hospitable the enchanted vocalists could be. Be the best or perish like the rest as most pods mantra tend to chant before eating an intruder.