Great article here by the BBC’s Matt Walker, reporting on new research to determine the origin of the silvery sheen that some birds’ feathers take on.
Led by Spanish scientist Ismael Galvan, the Spanish/Canadian research team was inspired to conduct the research following observations in the wild of the Lammergeier or bearded vulture. Lammergeiers are massive vultures of high peaks that obtain a significant amount of their nutrition from eating . . . bones. This habit, and their spectacular habitat, combine with their power, grace, and unique appearance to place Lammergeiers easily in the top 10 most awesome birds on the planet.
Now we have another hint at their awesomeness: Unusually long barbules – with an odd twisted structure, reflect light off certain body feathers to create the silver sheen. Lammergeiers are not alone in this barbule structure, but they do provide a great example of it.