As usual, I have no issue going against the grain here and proclaiming that half of these posts are knee jerk reaction responses based on "how you've always done it", which is fine, but predictable. I wouldn't say that I believe that it is unethical to shoot ducks after they have landed, though I rarely do it. If one lands and doesn't take off before I get reloaded though, then I sure wouldn't go out of my way to make it flush before shooting, unless there was danger of hitting a decoy or dog. To be fair though, I rarely decoy ducks. Maybe once every few years.
More to the point, shooting at flying birds I believe creates more opportunity for cripples just like shooting at running deer vs stationary deer---so there's that ethics angle to consider. Pellets can really be slowed down by water though which can also cause cripples I guess. That adds more levels of ethics to the situation.
It is outside of the point of this post since the OP is talking about decoyed ducks, but try stalking mallards (or wood ducks as in the OP's example) and getting a shot off without them knowing you're there. I believe that is WAY tougher than shooting them as they have their wings cupped. To my thinking, sneaking up on resting birds is way more of a challenge than blasting them out of the air, which is just shooting if you didn't do the calling or decoy placement.
