Identifying birds is really about understanding birds. Being attuned to the basics of bird behavior can help us put a name on species. Spring is the time of courtship behavior. Singing birds surround us, and their songs offer multiple clues to their identity.
We humans interpret birdsong as a joyous outpouring — a celebration of the end of winter, the reawakening of spring, the return of warmth and light. To birds, it is mostly a form of advertising, a macho display for potential mates and rivals. Each singer wants to be noticed, and most species try to be conspicuous using both sight and sound.
But not all the time. Birds have to balance their drive to stand out with a competing requirement to be inconspicuous. They need a badge, a visual signal that will be noticed only when they really want to be noticed.
The red shoulder feathers of Red-winged Blackbird are a good example of a contrastingly colored badge. The epaulet can be hidden beneath black feathers when it isn’t needed, and expanded into a bold flash when the blackbirds are displaying.
You’ve probably already noticed that most small songbirds have bright colors or a bold pattern on their throat. When a bird starts to sing, it sits up, throws its head back, and puffs out its throat. In bright light, its colorful throat feathers are put on full display. But as soon as the bird stops singing, it compresses the feathers, and they immediately become relatively inconspicuous and drab, shaded on the underside of the head.
Many species — from Blackburnian Warbler to Common Yellowthroat to White-throated Sparrow — show off colorful throat feathers as they sing. Even relatively plain species like Swamp Sparrow or Carolina Wren display a bright white throat when they vocalize. And it’s possible that even some plain brown species are showing off visually when they open their bill to sing. Winter Wren, for example, exhibits a pale yellowish lower mandible.
Think about visual signals as you watch singing birds this spring. Delving into the nuances of bird communication will help you become a better birder by seeing the world through their eyes.
This article from David Sibley’s “ID Toolkit” column appeared in the March/April 2014 issue of BirdWatching.