Hummingbird's Head Plumage (IMAGE) University of Bonn Caption The radiant emerald green is a result of the light-refracting nano-structures inside of these feathers. At the same time, their flat, consistently branching structure works to produce the striking metallic sheen. This specimen is from the collection housed in the Institute for Zoology at the University of Bonn in the Poppelsdorf Palace. Credit Photo: Georg Oleschinski/Univ. Bonn Usage Restrictions This photo may be used with the press release. 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.