I showed my wife a feather I found in the grass under our big tulip tree. Recognizing it immediately as a primary wing feather shed by a blue jay, we marveled at its superb design. Birds keep their feathers clean and in the best condition possible. For these creatures, feathers are life insurance.
Flight feathers are particularly important. Each feather in a bird’s wing is specially designed to fit perfectly against its adjacent feathers. Wing and tail feathers overlap like the slats in a window blind. The wing feathers unite for the downward power stroke and separate for the upstroke in each wingbeat. The feathers in a bird’s tail overlap so the tail acts as a brake or a rudder, with the central tail feather on top and the side feathers overlapping underneath on either side. It is a perfect, closable fan.
Feathers are built for easy maintenance. The central quill is very strong yet flexible. The webs that extend on either side of the quill are composed of individual fibers with barbs that catch against each other, like Velcro. When a bird musses its feathers, it can repair any damage simply by running its beak along the main shaft and the barbed webs slip into place.
In the drawing, notice how the feather tips of the spread wing open like fingers on a hand. The trailing edges of the five foremost flight feathers are notched so the tips of the feathers separate to catch the wind, while the bases still overlap.
When a bird sheds one primary wing feather, the corresponding feather on the other wing falls out at the same time. This balances the gaps so that a missing feather doesn’t hinder the bird’s flight. It takes a week or more for new feathers to grow out, so the all-important wing and tail feathers are replaced very gradually. In most birds, the hindmost flight feathers are the first to be shed and replaced. Then the next two flight feathers are shed, and the process repeats, until all primary flight feathers on both wings are brand new.
Growing feathers are soft and often bluish-colored because they are wrapped in a sheath similar to thin plastic. Called blood or “pin feathers,” they’re very sensitive and must be protected from injury. As a new feather grows, a bird spends a lot of time running its beak along the hardening shaft to peel the outer sheath off the growing feather. When the big quills of the flight feathers are fully grown, the quill hardens.
Looking at the sketches, it’s easy to determine exactly where each feather comes from. On a blue jay’s wing, the bright colors are on the part of the feather that shows, called the outer web. And the dull colors are on the inner web, the overlapping, hidden side of the feather. The inner web of each primary feather has a white area at the base, creating a white band visible on the underside of the spread wing.
From the pattern on the jay feather we found, we could tell that it was the outer primary next to the very tip of the right wing, one of the last two primaries to be replaced this season.
Doug Pifer is an artist, naturalist, and writer. He has a Master’s Degree in Journalism from Penn State and has been an editor and art educator. His illustrations have appeared in various books and magazines and he has been a contributor to The Observer for several years. He lives with his wife and assorted animals on 5.7 acres in a historic farmhouse near Shepherdstown, West Virginia.By Doug Pifer