I have a pair of call ducks, and this is my first winter with them. I've never had ducks or waterfowl before, so this is all new to me. It's gotten very cold here, and the ducks haven't been able to bathe in a couple of weeks. They are given a fresh bowl of water twice daily for drinking. But I didn't think that they'd want to bathe with temps in the teens/20's. Must they have access to a swimming area in order to breed?