What birders should know about wing feathers

wing feathers
A fluffed-up Chipping Sparrow, with its greater coverts shaded blue. Art by David Sibley

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.

Another view of a Chipping Sparrow, with greater coverts shown in blue. Art by David Sibley

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.

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David Sibley

David Sibley

David Sibley writes the column “ID Toolkit” in every issue of BirdWatching. He published the Sibley Guide to Birds in 2000, the Sibley Guide to Bird Life and Behavior in 2001, and Sibley’s Birding Basics in 2002. He is also the author of the Sibley Guide to Trees (2009), the Sibley Guide to Birds-Second Edition (2014), and guides to birds of eastern and western North America (2016). He is the recipient of the American Birding Association’s Roger Tory Peterson Award for lifetime achievement in promoting the cause of birding and a recognition award from the National Wildlife Refuge System for his support of bird conservation.

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