Aw thanks for the advice guys, kinda keeping her at arms length now, but yesterday another hithero unknown female showed up and now they're both quite content just following one another around.
If she somehow has ducklings again, how is best to avoid death from above via one of the falcons that occasionally circle the island? But in a way that feels natural to them.
And yes, the birdlife here is ridiculously okay with getting up close to humans. It's kinda magical, just a shame when a cat gets on the island. Place is suddenly littered with headless bodies of adolescent birds. Very upsetting