Tell apart from song or in flight by yellow bar on the secondary feathers below the wing, present only in the Russet Nightingale-thrush.

When flying, the Australian Wood Duck is the only duck with white secondary feathers and dark wingtips.

Four or five days after hatching, the young is skinny, blue-gray in color and only has its secondary feathers.

The western Spotted Towhee has white spots on its primary and secondary feathers.

Birds in more than 40 non-passerine families seem to be missing the fifth secondary feather on each wing, a state known as diastataxis.

In flight both sexes also show distinctive white secondary feathers, a feature shared only with the related genus Coturnicops.

The forewing of Anchiornis was composed of 11 primary feathers and 10 secondary feathers.

The secondary feathers and wing coverts may have gray margins.

When a jacana is in flight, its yellow primary and secondary feathers are visible.

They should be well closed and not show a "sail like effect", that is caused by raised secondary feathers that break the smooth wing line.