Male Anna's hummingbird at even higher resolution.

Male Anna's Hummingbird (Calypte anna) in repose at feeder

My beautiful wife captured our best hummingbird pictures yet this morning (click bird for higher resolution view). Notice the fine detail in the feathers. This male Anna's hummingbird, like many male hummingbirds, has a bright red neck when viewed from certain angles. I am uncertain whether this depends upon the orientation of the feathers, the orientation of the sun, the orientation of the person viewing, or some combination of those three. In any case, the geometry of this bird was right to show the red throat. From other angles, the throat of the male appears dark or black. (The throat of the female is much paler. See some of our previous photos in older posts).

This species, Anna's hummingbird (Calypte anna), is the only hummingbird species in which the crown (top of the head) of the male can also appear crimson (in addition to the throat). If you look carefully at the photo above, you can see a few reddish feathers on the head. Google image search for "Anna's Hummingbird" and you will find many images of male birds in which the entire head glows with a brilliant magenta color. You have to view the bird from just the right angle to get that effect.

On the lower left of this bird's throat is a region that is yellow-green, almost the exact complementary (opposite) color to the red-magenta seen on the rest of the throat. I suspect that the complementary color viewed from a different angle is no coincidence. It reminds me of the cytological stain eosin, which is colored red-magenta when you view light through the solution, but is yellow-olive when you view light reflected off of the solution's surface. Eosin is one of the important stains used in Pap smears, and many other important microscopic tissue staining methods.