The color purple

Today a delightful couple from Houston visited, Kevin and Emily McGowan.

All this month, ever since the Lucifer Hummingbirds have arrived, I've been bedeviled by the gorget color of either one individual, or something in the air causing all the males to look more purple at times.

Kevin is a photographer, though not a bird photographer, and while he was here he captured a bunch of images of the particular shade of purple that I've been obsessed with this month. He most generously allowed me to post one of his photos here. This bird is obviously banded, so I would think if it had a different color gorget, Kelly would have noticed. I do realize that gorget feathers aren't colored, but their color is a result of the light. As one author on the subject stated:

Hummingbirds aren't the color that they appear to be. That is, their feathers contain a pigment that is one dull color. The pigment is melanin. The colors that you see, such as blues, greens and reds are a result of several things including: 1) diffraction of light due to the regular spacing of the particles of melanin, interrupting certain colors; and 2) absorption of the remaining colors by the pigment

OK, I get it. But what is it about this month, or this particular bird, that makes it look so blue-purple regardless of the lighting, or angle?

Photo courtesy Kevin McGowan

Here is what they look like in previous years.

The only thing I can figure out is this March has been more humid than normal and maybe that's the difference. Perhaps by the time the summer rains arrive the gorgets are more worn, thus not as sensitive to humidity. A lame hypothesis, but all I can come up with unless there's just something different about one particular male's gorget feathers that refract light different.