Mountain Bluebird by Gerald Romanchuk
Why are bluebirds blue?
Unlike other plumage colors, the blue color of bluebird feathers is not due to a pigment. Rather, it is produced by the unique structure of the feathers themselves and the way they refract the light spectrum. If you take a bluebird feather and crush it, it turns dull gray. Adult bluebirds look different to each other than they do to us because birds’ eyes can detect color in the ultraviolet (UV) light spectrum. UV waves are invisible to the human eye. This UV coloration may play an important role when it comes to how the birds “see” each other.