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| Costa's Hummingbird, taken at Indian Wells today, Oct 28, 2012 |
I have never seen this species of hummingbird before. I chanced upon it in the grounds of the hotel where I was staying this weekend. It is a desert bird, named after a French ornithologist. Like all hummingbirds, the male has a spectacular metallic sheen to the feathers in its head and gorget.
Why do they look so cool?
The following is taken from asknature.org:
"To summarize, hummingbird iridescence is due to interference colors produced by a stack of about three films whose optical thickness is one-half the peak wave length. Each film is a mosaic of platelets of elliptical form. Each platelet is about 2.5 microns long and one micron wide. The platelets are not homogeneous and consist of air bubbles encased in a matrix of refractive index about two." (Greenewalt et al. 1960:253)
Greenewalt CH; Brandt W; Friel DD. 1960. The iridescent colors of hummingbird feathers. Proceedings of the American Philosophical Society. 104: 249-253.
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