I drove over to Middle Creek Wildlife Management Area in Lancaster, Co. PA early this morning to get a look at this beauty. It's a Mountain Bluebird, fairly common in the west but very rare in the east. In fact, the bird at Middle Creek is only the sixth record of a Mountain Bluebird in Pennsylvania.
The photo is not of the same individual that's at Middle Creek, but it's the same species. I've seen them at very close range (today's bird was a couple hundred yards out) in Montana and Colorado, and the blue just takes your breath away. An interesting fact about this is that in birds blue color, unlike most other colors, is not due to a pigment. In fact, the feathers of birds like the Mountain Bluebird are actually colorless. The appearance of color is due to the structure of the feather which causes the light to reflect in such a way that most of the waves cancel each other out, leaving only the blue light to travel to your eye. A common blue bird in the east in summer is the Indigo Bunting, which superficially resembles the Mountain Bluebird, but as brilliant as its color appears, it's not due to pigment but to wave interference which cancels out the other colors of light.
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| Indigo Bunting |
Compare the two pictures and see if you can tell how the two birds differ.
