My brother rented this game (it sorta scares me) and I figured out a way to kill those stupid duck things. First go to that farm or whatever it is, weree those annoying birds think your a security guard (they shoot darts at you if you hurt them to put on the invincibility cheat) at onbe side of the farm, there is one of those things that squishes things wen you put a zappfly or whatever on the switch.

Make one side of your bow empty (so you can punch those do-dos lol) and the other one a zappfly. Puch a duck thing under the giant thing thaty squoished you and hurridly press the button and he will get squished it makes me happy cause those guys are so annoying!

I have discovered that if you use the thudslug and the zapfly (fully charged) you can knock out a boss easily so you will be able to get the full bounty. You could do that or use what I call the tornado, just keep tapping the left trigger and he'll go down.