Pickpocketing.

[No, really. Did you think he was kidding about the 'thieving' part?]

One knocked me into the dirt and then stole the potion I had in my coat pocket right out of it. Throwing out ideas of 'normal' is probably a good idea because no ducks I know of have hands. I think Cor might be right in suggesting they may be more like the Pokemon from Will's world than normal animals.