Simple trick while building a walk-cycle, to switch between the character walking a) in place and b) along the ground.
When you copy animation from a child to its' parent and then inverse the animation, it negates the move altogether. In this case, we want the duck's feet stick on the ground. You can use this idea for many other rigs. This tutorial is in Softimage, but also applies to Maya, etc.
“Dadi Einarsson showed me this trick when I was a youngster in animation -- just passing it on.”