I thought swans were protected. And such you are not allowed to disturb them.

I sort of recall one of my co-workers many years ago of telling me a story where a hunter shot at a flock of geese in flight. The poor hunter's dumb luck brought down a swan instead. And add more insult, there happened to be a game warden who witnessed the whole thing. Hunter had his shotgun confiscated, and fined something like $8,000 for killing a swan. My co-worker wasn't the kind to make up stories like that so I believe him

Next time call a game warden.