Nothing Common about This Eider (IMAGE) University of Delaware Caption A type of duck known as a common eider swims near a sensor, perhaps waiting for a worm, which is used as a reward for pecking the sensor after hearing a ping. Credit Kate McGrew Usage Restrictions None 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.