Feather Identification: What Bird Feather Is This?

Position first, species second. The Feather Atlas, run by the U.S. Fish and Wildlife Service's National Fish and Wildlife Forensics Laboratory, is organized around flight feathers for exactly this reason, and its identification tool asks you to search by pattern, color, size, position and type of bird.

The positions are few. Primaries are the outer wing feathers attached to the fused bones of the bird's hand, and most groups of birds have ten. Secondaries are the inner wing feathers attached to the ulna, and their number is highly variable, from nine to twenty-five. Tertials are the innermost, attached to the upper arm, usually three or four. Rectrices are the tail feathers, most commonly twelve.

A soft, fluffy feather with no firm vane is a body or down feather, and those are not in the Atlas. Flight feathers are the ones that can be identified.

Look at the two sides of the vane on either side of the shaft. Wing feathers are asymmetrical: the outer vane is narrower than the inner. Tail feathers run from strongly asymmetrical at the outer edge of the tail to symmetrical in the middle, and the two central tail feathers are usually exactly symmetrical with a perfectly straight shaft.

Within the wing, primaries usually have pointed tips while secondaries have rounded or squared ends, and the shafts of secondaries are often curved.

Two more details are worth knowing. An emargination is a distinct narrowing in the front vane of a primary, and a notch is a distinct narrowing in the rear vane; both are used in identification keys. A tegmen is a shiny, waxy-looking patch along the shaft on the underside of a primary, found in waterfowl and some other groups, and it tells you which face of the feather you are looking at.

Once you know the position, pattern does the rest. Broad crosswise bars point to hawks, owls, flickers and many gamebirds. Plain feathers with no bars point to crows, ravens, blackbirds, doves and many songbirds. A white base with a dark tip, or the reverse, narrows things quickly. Iridescence that changes color as you tilt the feather points to grackles, starlings, hummingbirds and the speculum feathers of ducks.

Measure the feather in millimetres, not by eye. The Feather Atlas provides a table of total feather lengths and vane lengths for each scan, along with the age, sex and locality of the specimen, so a measured length is directly comparable. All scans were made at 600 dots per inch, and each species page shows the feathers of the right wing and the right side of the tail, with the outermost feather on the left. Left and right tail feathers are mirror images of each other.

Use the location and season as a filter too. A feather is only useful evidence if a bird that could have dropped it occurs where you found it.

In the United States the possession of feathers and other parts of native North American birds without a permit is prohibited by the Migratory Bird Treaty Act. The Feather Atlas states plainly that there is no exemption for molted feathers or for feathers taken from road-killed or window-killed birds, so how you obtained the feather does not change the position.

The exceptions the Atlas lists are narrow: feathers of legally hunted waterfowl and other migratory gamebirds, and the use of feathers by Native Americans. Individuals and institutions that want bird feathers, bones or whole specimens for education or research have to apply for permits.

Separately, a small number of non-native species are not covered by the Act at all, among them the House Sparrow, the European Starling and the Rock Pigeon, because the Act does not apply to species present in the United States solely because humans introduced them.

The practical answer for a found feather is to photograph it where it lies, measure it against a ruler or a coin in the same frame, and leave it. Photograph it and the app identifies it, and nothing has to be collected.

Lay the feather flat on a plain background of the opposite tone: a dark feather on white paper, a pale feather on something dark. Shoot straight down, with the whole feather in the frame from the base of the shaft to the tip, and include a ruler or a coin along the shaft.

Take a second frame of the other face. Many feathers look completely different from above and below, and the underside is where a tegmen shows on waterfowl primaries.

Use diffuse light, near a window on an overcast day rather than in direct sun. Iridescence in particular changes with the angle, so take two or three frames from slightly different positions if the feather shifts color as you move.

Yes, a feather can be identified from a photo, as long as the photo shows the whole feather flat and something of known size beside it. The Feather Atlas search tool works from five things you can read off a good photo:

• Pattern: unpatterned, two-tone, mottled, barred, spotted, iridescent, dark tip or pale tip. The Atlas notes that many feathers are best described by more than one pattern.
• Color: white, black, black-and-white, brown, gray, blue or purple, green, yellow or orange, red or rufous, pink.
• Size: small is up to 8 cm, medium 8-16 cm, large 16-24 cm, huge over 24 cm.
• Position: primary, secondary or tail feather, as described above.
• Bird group: eleven groups, from waterfowl and raptors to owls, woodpeckers and songbirds.

The size class is the one a photo without a scale cannot give you, and it removes most candidates. That is why the coin or ruler matters. Photograph the feather and BirdLens suggests the bird; then open the Atlas scans for that species and compare the length and pattern.

Three kinds of feather account for most searches.

• Hawk feathers: broad crosswise bars on a brown or rufous feather point to hawks, but also to owls, flickers and gamebirds. The hawk feather identification page covers the raptor groups and the separate eagle law.
• Owl feathers: soft edges and a comb-like leading edge on the outer primary are the owl giveaway; see owl feather identification.
• Black-and-white feathers: in the Atlas tool, choose the black-and-white color and then try both two-tone and barred patterns, because the tool treats them as different searches.

All three groups are native birds, so the Migratory Bird Treaty Act covers their feathers, hawk and owl feathers included.

A feather identification app gives you a fast first guess from a photo; a reference collection is how you confirm it. Use them in that order.

• BirdLens: photograph the feather flat with a coin or ruler beside it and the app suggests the bird. The scale matters, because size class removes most candidates.
• The Feather Atlas: free, run by the U.S. Fish and Wildlife Service's forensics laboratory, with flight-feather scans for 438 North American species. Its Identify My Feather tool searches by pattern (eight options, including barred, mottled, iridescent, dark tip and pale tip), ten colors, four size classes from under 8 cm to over 24 cm, position, and bird group.
• Merlin Bird ID: free, and identifies birds from a photo, a sound or a description, per The Nature Conservancy. It is useful when the bird that dropped the feather is still around.
• HawkWatch International's app: free, with nearly 1,000 annotated raptor photos, for the case where you suspect a hawk.

What no app can tell you is whether you may keep the feather. In the US that depends on the species, not on how you found it, and the answer for native birds is no without a permit.