More Than Meets the Eye

Gray, gray, gray.  The gently rippled surface of the lake was gray in the early morning calm. Gray fog and gray clouds hung low over the gray trunks of the trees. Then a dark shape materialized out by the buoy. Shifting slightly, it revealed the white throat of a loon glowing through the gloom. As I watched, the loon dipped its face into the water, peering into the depths below. What it saw I cannot imagine, but its purposeful dive suggested fish by the rock pile. The loon’s sudden appearance and dive remind me that there is more to this silent gray lake than meets the eye.

Chick-a-dee-dee-dees in the balsam fir tree next to me reeled my mind’s eye back up from the depths of the lake. The flock from my bird feeders had followed me down to the lake for breakfast. I pulled a few sunflower seeds out of my pocket and extended my hand toward the birds.

With a whirr of wings, the first chickadee swooped from the fir tree and landed on my fingertips. Tiny toenails pricked my skin and one shiny black eye looked up at me from a cocked head. We examine each other tentatively.

I always feel a thrill when such a fluffy ball of wildness lands on me. I love the chance to see chickadees up close. Their backs are not pure gray, but tinged with a warm beige around the neck that spills over onto their sides. The edge between black cap and white cheeks is not smooth, but shows finely divided feathers. The base of the black throat patch where it grades into white belly feathers is even more irregular.

The frustrating part is that although this is my third winter feeding chickadees from my hand, I still can’t tell them apart. I am not even aided by markings that indicate male and female birds. So, I wonder, how do the chickadees know whom to romance in the spring?

We have long known that many birds can see ultraviolet light, but it took scientists a while to decide to test the UV reflectance of their feathers on a broad scale. In one study, scientists tested 139 species of birds that we believed to be “sexually monochromatic.” In other words, they tested birds that humans cannot identify as male or female by their colors. The study found that more than 90% of birds tested had UV reflecting feathers, and were “sexually dichromatic” from the avian perspective. Of course birds can tell each other apart!

My neighborhood chickadees are part of this pattern. If we could see in the UV spectrum, we would know that the males are brighter white and deeper black than females. Females prefer males with the sharpest contrast between white and black patches, which reinforces the trait in each generation. Males also have larger black patches, which we could potentially observe if we looked carefully. Interestingly, males with bigger black bibs tend to have more reproductive success.

With a quick dart forward to grab a seed, the chickadee on my hand whirred off to a branch in a flourish of gray. As other members of the flock flitted around in nearby trees, I marveled at my thoroughly human-centric view of the world, and tried to imagine life with another color in my vision. Just then, the loon surfaced through the mirrored surface of the lake. There is so much more to this world than what meets the eye, especially for humans.