Did you make every stage at hand or did you create a system (maybe AI) for the running duck abstracted from every stage so you could fit his behavior in any stage easily?
I am a software engineering myself.
I hope you tried to do something like this: http://jceipek.com/Olin-Coding-Tutorials/pathing.html and also paying attention to the article in the very ending (steering) .
I think people use to choose a path finder algo for each difficult level, adapted to game engine and also other mechanics, like the duck grabbing.