SERIOUSLY??? You are going to actually make an EXCUSE for him OR these so-called 'hunters'????
Here is what you do if you aren't sure what species the bird is.......DON'T SHOOT.
That being said.......ALL ducks are 'protected'........the article isn't clear if they were ducks permitted to be shot (like mallards) or ones that were not (like cormorants).
Guides who break the law should be subject to prosecution to the fullest extent of the law.....ESPECIALLY when knowingly do it.