Structural Colors: The Art of Photographing Hummingbirds

Nature is full of color. However, color is not an unshakeable property of an object. Something’s color will change depending on various factors, including the wavelengths of light that hits the object, the object’s absorption and reflection of those wavelengths, and finally, our own eyes. In this article, I will show you how color can vary with one subject in particular – the hummingbird – and how I approach photography with structural colors in mind.

First, I have a simple question for you: How does color perception occur? Well, simple may be deceptive. Color is a complex phenomenon. But it starts with a source of light, such as the sun.

Every moment, the sun emits photons which have to travel about 150 million kilometers across the vacuum of space before they finally reach the Earth. After eight minutes or so, they hit the objects around us. Depending on the nature of the object’s surface, certain photons are reflected, and the rest are absorbed. With 6 million receptors in the retina of our eyes, we pick up these reflected photons, and our brain translates them into objects – shapes, sizes, and colors.

Take even the most colorful hummingbird into a dark room, and its colors would fade like the leaves in autumn. Where there is no light, there are no colors. But let’s bring the hummingbird back into the daylight.

Our eyes can only pick up a narrow slice of electromagnetic waves, ranging from about 380 to 700 nm. To our eyes, these different waves appear as colors. On one end is violet (around 380-450 nm) and on the other end is red (around 610-700 nm). In between are blue, green, yellow, and orange – while most interestingly, magenta stands as a combination of red and blue wavelengths, and does not have its own wavelength of light.

It may not surprise you to learn that many animals, such as birds and some insects, can see a much wider range of colors than we do. But others might envy our color perception. Horses can only see combinations of yellow and blue, while the humble mantis shrimp can see both UV and IR light without breaking a sweat.

On the other side of this discussion is the light that animals reflect. Have you heard of the green plant pigment, chlorophyll? Or the pigment melanin that affects our skin tones as humans? There are just two of the many pigments in the tree of life. Animals have at their disposal carotenoids, lipochromes, porphyrins, and other pigments that give them their unique colors. These pigments aren’t just for show – they can be essential for survival. Among other benefits, pigmentation helps an animal camouflage itself, attract a mate, or warn potential predators of danger.

Pigmentation, however, is not the only way a living thing can change its colors. There is also the structure of the animal’s surface – leading to structural color – and it’s my reason for writing this article. Many animals, including hummingbirds, have surface structures that can act as sophisticated (and microscopic) mirrors. If you magnify the wing of a hummingbird or the shell of a beetle enough, you will see a complex labyrinth of microscopic pores that give the animal its structural colors. Butterflies, peacocks, ducks, and many others have the same sorts of features.

If you want to study these delicate structures, a typical microscope won’t help. After all, the light-absorbing pores are only a few hundred nanometers across, so you’ll need a scanning electron microscope that can magnify more than 1,000 times. I don’t have such a microscope, but science photographer Petr Jan Juračka does. Here you can see his unique photographs of butterfly wings and read something interesting about them.

Unlike pigments, which typically deteriorate quickly over time, structural colors can last for ages. There have been found fossils of long-extinct beetles that still have their original colors intact.

Let me return to the mirror analogy. Structures on an animal’s surface, thanks to their spatial arrangement, are able to reflect colors in the desired direction. It’s like reflecting a beam of light with a mirror into someone’s eye. A slight change in angle, and the light (or color in this case) is deflected elsewhere. Some birds, such as hummingbirds and birds-of-paradise, even use this effect for communication.

That’s right, bird feathers are not just for flying or protecting themselves from the harsh environment. Feather color also plays an important role in camouflage, breeding, and protecting territory from unwelcome visitors. Consider the Brown Violetears. By spreading their colorful “ears” and adopting an expressive posture, they can send a clear message that an intruder is not welcome.

Finally, let’s look at pigment and structural colors through the eyes of a photographer. With structural colors, the direction of the light plays a big role, and the animal’s appearance can change significantly if they just turn their head, or the light changes slightly. Pigment colors, on the other hand, are much more predictable. The yellow coloration of a tanager (a pigment color) will be yellow from all angles, and it will remain yellow even if I use artificial flash on it.

And here I come back to the title of this article, “Structural Colors: The Art of Photographing Hummingbirds.” In the pair of photos below, I’d like to show you what your hummingbird photos will look like if you use a flash attached to your camera. (Let’s ignore the other effects of flash on the scene you’re photographing and just focus on the hummingbirds.)

Notice that the color of the bird with flash is very different from natural light. In particular, the green tones of the feathers tend to fade to bronze under the onslaught of the flash. Many shades are lost completely. This is because suddenly, many microscopic mirrors are pointed in your camera’s direction, making the bird pop unnaturally from its surroundings.

So, what to do when photographing hummingbirds, or other animals with structural colors? Look for diffused light, and don’t be afraid to increase the ISO. Or, if you do use a flash to photograph hummingbirds, do so with a large diffuser – and use multiple off-camera flashes if possible.

To my eye, hummingbirds are best photographed in diffuse sunlight. Of course, it is possible to photograph them in direct sunlight or with a flash and still get good results. But if you aren’t careful, harsh light can mask these lovely structural colors.