The colors and patterns of feathers provide some of the most important clues we have for identifying birds and are generally quite reliable. Only a few things alter the appearance of feathers. They become worn and faded over time. They can be temporarily shifted out of place, disrupting the typical color pattern and sometimes revealing an unexpected grayish or whitish color of the exposed feather bases.
Feathers can also become stained or discolored by external substances, and the most common of these is simple water. Feathers are water repellent, and water usually just rolls off (like water off a duck’s back), leaving the feather unchanged. When feathers are subjected to a real dousing, some of the water sticks to the feather, and they become wet. This happens most often when water is somehow pressed into the feathers: sparrows pushing through wet grass, doves exposed to an extended heavy downpour of rain, or warblers taking a bath.
The surface of a dry feather is a fine mesh of reflective surfaces. When water saturates that mesh, the appearance becomes darker, and the barbs that form the rounded tip of a normal feather are pulled together in clumps, forming a ragged and pointed shape.
Once you’ve seen a few wet birds, it’s usually easy to recognize the condition and make allowances for it as you work through an identification. However, if you’re not expecting it or don’t realize that a bird is wet, it can be quite confusing. Because the feathers on a bird’s body are arranged in an organized pattern, the dark and pointed tips of wet feathers often line up to form what appear to be dark streaks, dark lines around the face, or other patterns. And when the barbs at the tip of a feather clump together, this can expose the pale gray or whitish base of the feather below, which is normally concealed by the broad rounded tip of a dry feather.
The solution to this challenge, as in so many other bird identification challenges, is to be aware of the possibility, look at multiple features, and keep an open mind. With practice, this will become second nature.
This article was first published in the July/August 2021 issue of BirdWatching magazine.
Watch a PBS video about how water rolls off a duck’s back
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