In ornithological plumage description, the upper and lower edge feathers in the area of the upper arm are called humeral feathers(pennae humerales, parapteron, remiges tertiarii). These are three to four feathers located proximal to the innermost arm wings. In birds with long wings, humeral feathers fill the gap between the body and the arm wings that occurs when the wings unfold.
In some bird species, they are characterized by special features that distinguish them from the other arm feathers in their identification. The best known example are the humeral feathers of the cranes (Gruinae), which are formed into decorative feathers. In the Grey Crane(Grus grus), when the birds are on the ground, they are brown, grey or anthracite coloured and project above the relatively short tail like a train. In young birds in the first year of life, this plumage form is only rudimentary, but nevertheless already very clearly recognizable present.
- Noble S. Proctor, Patrick J. Lynch: Manual of Ornithology: Avian Structure & Function. Yale University Press, 1993, ISBN 978-0-300-07619-6, p. 58.