For the birds

I remember a cartoon from my youth. Bugs and Daffy were on a bridge. A portable hole fell on the bridge surfaced and Daffy fell through. Bugs looked t the camera and said "I wonder if Daffy will remember he is a duck and can fly." ... Splash! "Nope."

Why didn't the duck fly across the road? I didn't get a chance to ask before he was hit. Perhaps flying is simply too costly in evolutionary terms. Perhaps ducks are programmed to use whatever means of transportation works in order of swim, walk, fly needed to get from A to B. Perhaps it is a simple jiggering of priorities required.