If you’ve read my blog for very long, you’ll know that hummingbirds make frequent appearances. I love those little guys. Even more, I’m amazed by them. How they fly, how they hover Hummers Are Back, how they eat Eyelashes and Hummingbird Tongues, the fact that they have to eat constantly when they are awake Hungry Hummer Can’t Wait. They are just generally cool.

One of the most interesting things about hummers is that the iridescent colors of their feathers aren’t created by pigments, but rather by the way the light shines through them.

The red “gorget” on this male broad-tailed hummingbird is so intense that it is hard to believe that it isn’t a pigment.

Instead, iridescent feathers are built like prisms that only let red light through, and only from certain angles.

Here is the same bird when he turned his head:

All that changed was that this guy turned his head to give me a nice profile shot. But when he did, the angle of the light changed.

When this male broad-tailed hummer turned his head, the angle of the light changed, and his gorget showed that it had no pigment in it at all! It’s all just a pigment of your imagination! (Sorry, bad joke.)

Many hummingbirds have iridescent feathers on their backs tuned to green.

Female broad-tailed hummingbird.

The calliope hummer in Eyelashes and hummingbird tongues had a gorget of magenta, but I could never catch the light coming in the right way, so it looks like a ragged black collar.

This ability to show us colors without using pigments is a trait shared by a lot of birds. Blue then Black Magpie follows me on the trail.

Interestingly, although some dinosaurs may have iridescent (Microraptor Was A Glossy Dinosaur), no mammals ever developed the trait.