Summer Tanager (IMAGE) Cell Press Caption Scientists have identified the gene that allows birds, such as the Summer Tanager, to produce red coloration in feathers. In this yearling male, the redness gene was turned on in some feather follicles yielding red feathers and turned off in other follicles yielding yellow feather. Credit Geoffrey E. Hill Usage Restrictions Credit Required. 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.