Wing patterns might seem complicated at first glance, but the good news is that the arrangement of wing feathers on all kinds of birds is quite similar (and is nearly identical on all songbirds). So learning the feathers on one bird will unlock a trove of information about other species.
Among all of the feather groups birders talk about, the wing coverts are one of the most important. They are easily identified and often distinctively patterned, and once you’ve located them, they provide a reference point to understand other details of wing pattern and structure.
Functionally, the wing coverts help to streamline the wing during flight by covering the bases of the big flight feathers to form an airfoil shape. Coverts are aligned in rows, beginning with tiny feathers along the leading edge of the wing and rows of progressively larger feathers farther back. The largest wing coverts (the greater coverts) are found around the middle of the wing and overlap the bases of the big flight feathers. The next row forward (called the median coverts) is made of smaller feathers and overlaps the bases of the greater coverts. The next row is of smaller feathers (lesser coverts), and these continue in smaller and smaller rows right to the leading edge.
When the wing is folded, the greater coverts form a roughly diagonal patch around the middle of the folded wing. Only the long flight feathers extend behind them. The smaller coverts, arranged in front, are often hidden under fluffy body feathers. One thing that helps to distinguish the coverts from the body feathers is their texture. Body feathers are loose, fluffy, broad and curved, while coverts are stiff, narrow, and flat. Even as the feathers on the rest of the bird move around, the arrangement of wing feathers stays more or less the same.
Once you’ve located the greater coverts, you can learn a lot by studying the details of their colors. Wingbars are formed by pale tips on the greater and median coverts. Some species have broader pale tips on the greater coverts, some have broader tips on the median coverts, and some have only one pale wingbar. Some species have a pale margin along the entire length of each covert feather, others do not.
Like any in-depth study, focusing on one detail like the wing coverts can lead to insights about other details — and a better understanding of the whole bird.
A version of this article was published in the May/June 2019 issue of BirdWatching.