Birders rely on a variety of characteristics to identify birds. Ideally, plumage colors and patterns are the primary means for recognizing a species, but sometimes plumages cannot be seen very well.
What about that backlit bird perched at the top of a tree or shrub, appearing as nothing more than a silhouette? There are still ways to figure out what that bird is.
One way is to watch the bird’s behavior. I was reminded of this last week when I spotted Eastern phoebes, palm warblers, and American pipits at a local park. These three unrelated species share an unusual trait: They are all tail waggers, constantly wagging or bobbing their tails as they forage or perch.
Why some birds wag their tails is not completely known. It has been noted that our local tail waggers (and others worldwide) are associated with open or semi-open habitats. Perhaps the motion of the tail casts a moving shadow that flushes insects out of the grass. Another theory is that the tail movement aids in balancing when a bird is perched on a thin twig in windy conditions.
Eastern phoebes are fairly common right now in a variety of habitats, and they don’t seem to mind humans. Look for a dark and light gray bird that lifts and lowers its tail while perched on low limbs or fences.
Palm warblers are uncommon winter residents in our area, but look for them in weedy fields or expansive open lawns. They are relatively nondescript except for yellow feathers under the tail. The regular movement of that tail will surely tell you what it is if you encounter one.
Water pipits are small flocking birds of expansive plowed fields or pastureland. They are more often heard flying overhead than seen on the ground. If you do find some foraging, you will likely see that tail movement. Although most small birds hop, pipits actually walk. That behavior is also useful for identification.