Make a large cut when field dressing a turkey or large grouse so you can get your whole hand inside the body cavity.  This will make it easier to take the entrails out.   remove entrails with your hand.

In a smaller bird like duck, remove entrails with a bird gutting knife (knife with a hook on the end).  Insert the hook into body, then rotate the knife and pull it out.  The entrails will twist around the hook.  A small forked stick can be used the same way.