You are "stuck between a rock and a hard place". If your neighbor does not want to file charges, there is nothing the "authorities" can do.
Agreed - while the situation is frustrating and "wrong" in the view of those reading it and living through it, legally it is another issue. If nothing else, perhaps this can be the catalyst for you to speak with the HOA, etc and establish some ground rules regarding the ducks, etc - it may even be possible to have verbiage added to the HOA regulations that addresses the bothering of wildlife, etc. Does it fix this situation, no, but it can help to give you better standing to prevent such situations from taking place in the future.