Just as I was about to leave the one of the parks on the Mississippi River that I visited today, I heard bluebirds singing in a nearby tree, so I tried to track them down. They never let me get close, but the contrast of the males’ bright blue feathers against the rusty brown of old oak leaves was striking enough to make some nice photos.
My long-term blog readers may recall from earlier posts that the blue color is structural, rather than the result of a pigment. Tiny air spaces in the feathers contain particles (like dust) that scatter and reflect short wavelengths of light so that the feathers appear blue to our eyes. In the wrong light (i.e., indirect), the bright blue feathers just look slate gray.
Bluebirds are not very cold tolerant birds, and we may still experience more spring snowstorms and sub-freezing temperatures, so I hope these guys haven’t arrived too early.