Wing Feathers (IMAGE) University of California - Riverside Caption Photo of a broadbill wing, showing the P6 and P7 feathers that generate the sound. Credit Christopher Clark, UC Riverside. 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.