Eyes Like a Hawk? Or Like a Hummingbird?

This male Costa's hummingbird used color vision to find a patch of pink flowers. Image by Charles Kazilek.

Vision is a hummingbird's most important sense. The hummingbird is a fast flier that makes a lot of changes in direction. Without good eyesight, it would run right into things.

Furthermore, hummingbirds don't have a great sense of smell, and most species only make a few alarm calls and squeaks.

Except for the hermit hummingbirds, most don't sing elaborate songs to attract females or chase off rivals, unlike songbirds. This means that most hummingbirds rely on vision to let them find food and mates. 

This female black-chinned hummingbird seems happy to get a drink from a stalk of yellow flowers. Image by Charles Kazilek.

Hummingbirds see color just as well as humans. In fact, they can also see ultraviolet light, which means their world appears even more colorful than ours.

Does Color Matter?

Flowers are often colorful. Bright colors signal to the hummingbird that it might be about to find a tasty nectar snack.

Red flowers are regularly visited by hummingbirds, and many people use red feeders because they believe hummingbirds won't drink from a feeder of a different color. 

So why do hummingbirds flock to the red feeders? Is it the red color? Or could it be that hummingbirds are simply after the good source of energy, not a favorite color? (To test this idea, check out our hummingbird experiment.) 

Flashy Feathers

If you look at a perched male hummingbird, he might sport a loud patch of red. But if you move your head to the side, suddenly that bird may look purple, or black, or any number of colors depending on his species. What's going on?

This fiery-throated hummingbird in Costa Rica sports brilliant iridescent feathers all over his throat and chest. Click for more detail.

Many birds have colorful feathers because of the pigments contained inside. These are similar to the dyes that give your clothing color. However, you probably don't own any clothes that change color depending on how you look at them, and there's a good reason for that.

Feathers that change colors (called iridescent feathers) look that way because of what scientists call "structural coloration." This means that it is the structure of the feather itself and how it affects sunlight that causes it to look a particular way.

Sunlight is made of many wavelengths of light, which are responsible for all the colors we see. Feathers with structural color reflect, scatter, or absorb different wavelengths in different ways, resulting in changing color.

Additional images via Wikimedia Commons. Hummingbird feather by Brocken Inaglory.