Are these ducklings or adults or something in between?
I confess, domestic ducks on a pond do give me some concerns, since there are snapping turtles, predators that come to ponds for food, and hawks and eagles that can swoop down when a duck has no cover (granted, they might be able to dive, if they see the bird of prey in time).
Yes, I have also heard people say their ducks just won't come in at night from off the pond. It does not seem to be an easy decision to make. I go with keeping my ducks safe at night. Of course, we do not have a pond, so that makes the decision much easier!
Try the BYC search for "duck house float pond¨ and see if that gives you more details.
Please tell us more about your ducks! We love to hear about them, and if you have photo's, well, so much the better!