Peacock Feather Barbules (image) The Optical Society Caption This image shows the magnified barbules of a white peacock's feathers, which feature long appendages that diffuse thermal radiation to keep the birds warm. Credit Optics Express. Usage Restrictions None 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.