subalar

The beautiful subalar plumage is then thrown out and cleaned from any spot that may sully its purity by being passed gently through the bill, the short chocolate-colored wings are extended to the utmost, and he keeps them in a steady flapping motion, at the same time raising up the delicate long feathers over the back, which are spread in a chaste and elegant manner, floating like films in the ambient air.

In Nesting Time Olive Thorne Miller 1874