The speculum feathers are the inner (secondary) flight feathers of a duck. They are often brightly coloured, especially in dabbling ducks, and can help to identify a duck in flight.
Examples are:
- Common Teal: green
- Green-winged Teal: green
- Blue-winged Teal: blue
- Mallard: purple-blue edged white
- American Black Duck: purple-blue ( not edged white)
- Northern Pintail: greenish black, edged white at back and orange in front
- Gadwall: small and white, but only obvious in male
- Yellow-billed Duck: green or blue, bordered white