I agree it is a heartbreak to lose a duck, regardless of the reason. And perhaps you could tell us more about the restrictions on ducks. Some areas have contracts that say "no more than N number of animals," some say "no livestock," and so forth.
BTW, I found a nice house for sale many years ago, but the deal breaker was "no more than 2 pets." It was at the edge of a small Ohio town, right next to a farm!
I second this opinion--if it's illegal to keep ducks, you might not want to take the risk of getting caught. I had a ferret growing up and I've been wanting another one for years, but I haven't gotten one because I'm planning to move to California where ferrets are illegal. When it comes to ferrets in California, I know that if you get caught, they'll confiscate the ferret and often put it down. I don't know what the laws are where you live, but it would be tragic if the police took your ducks away! I'm not saying that taking the risk is wrong. I'm just saying it's something to seriously think about. How will you hide your duck? What about when it needs a vet?