Examining the Wing of a Blue-headed Vireo
Detailed Description
A biologist gently extends the wing of a Blue-headed Vireo to look for clues on how old the bird is. During fall migration, scientists can generally determine if a bird was hatched during the current year or if the bird is older. They do this by looking at the general wear of the feathers, and if the bird has retained any of their plumage as a nestling.
Sources/Usage
Public Domain.