Duck to Goose (IMAGE) Brown University Caption Waterfowl beaks vary along a duck-to-goose gradient (left to right), primarily because of differences in diet. Credit Aaron Olsen Usage Restrictions with credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.