Sometimes we come across loose feathers on the ground – sometimes a single feather, sometimes a group (which usually marks the feeding scene of a predator). Whatever the situation, the same question always comes up: which species lost these feathers?
The best way to start is to ignore color and study the shape of a feather instead. All birds share a similar structure and simple rules will help you determine which part of the bird a feather comes from. Knowing this, matching the color and pattern of a feather to a species becomes much easier.
Please note that the Migratory Bird Treaty Act prohibits the possession of feathers or other parts of a native non-game species. If you find feathers on the ground, you can handle them, study them and take pictures, but it is illegal to take any with you.
All feathers curve toward the tail, and if you find a feather that is mostly straight, it is probably a tail feather. The largest and stiffest feathers are on the wings and tail, and each has a distinctive shape that will allow you to determine exactly which part of the wing or tail it came from and (just for fun) which side of the bird.
All the large wing feathers (primary and secondary) curve backwards and downwards, and the outermost ones are strongly asymmetrical: the leading edge is narrower than the trailing edge and the tip is angled. The inner (secondary) wing feathers are also curved; the shaft is close to the center of the nib and the tip is square.
The outer tail feathers, like the outer wing feathers, are asymmetrical with a narrow leading edge and the shaft has a slight S-shaped curve. symmetrical.
All body feathers are smaller, symmetrical, flexible and rounded. They come out of the body and curl towards the tail. Feather size and length vary considerably, from short, stiff feathers around the face and at the leading edge of the wing, to relatively long, flexible feathers on the flanks.
Using these simple shape guidelines, you should be able to determine a feather’s location and then use color to narrow down possible species.
This ID Toolkit article by David Sibley appeared in the May/June 2017 issue of BirdWatching.