The feather needed further inspection so we brought it back to the building. It first glance it looks pretty plain. It is 5 1/2 inches long and brown. Look closer though, and there is more to learn. The feather is clearly from a wing as it is asymmetrical. This is thus a flight feather. Moreover it is from the right wing of the bird as the smaller (anterior) side of the feather is almost always the leading edge.
Look at the end of the feather, see how it is slightly pointed? This is called the distil tip of the feather. It isn't extremely pointed but it is something to note. I was assuming by the fairly narrow leading edge and the slight point of the distal tip that this was a primary flight feather (those further out on the wing) rather than a secondary flight feather (which are closer to the body). Judging by the fact that it wasn't very pointed, I was guessing that it wasn't one of the outermost primaries. Those tend to have the greatest points at the end.
Another thing to note is the coloration at the tip. It is subtle but there is a bluish hue just at the tip.
Time to head to Drawer 5e. "Assorted duck wings"
There are actually two drawers of duck wings at work, this is just one of them. You can see the great variety of wing shapes and colors a bit in this photo.
A little digging and it was clear which wing was a match.
Here's the feather placed on top in the correct position. This is the 7th primary feather from the right wing of a Wood Duck.
I was able to go though this process with the kids in my camp and have them help discover the identity of the feather's previous owner. It was a good example of why we have a natural history collection of everything from study skins to skulls. What if you don't have a natural history collection to call on?
I was able to find the same information in the book Bird Tracks & Sign : A Guide to North American Species. While it does not cover every species of bird you might encounter, it has a good section on feathers and the wood duck feather in question was easily identified from the book alone. You can click on the photo for a larger version but you an see it is the second feather on the right. This book not only has feathers but extensive text and photos on the tracks birds make on the ground. It is a very interesting resource for all you naturalists out there.
If you are very interested in identifying the flight feathers you find outdoors you might also want to pick up the book Bird Feathers: A Guide to North American Species. Though it focuses only on flight feathers, it has many more species of birds than the book above. It is okay to give into your book lust. You know you want them both.
Both books are easily available online and are invaluable tools on the naturalist's shelf.