Alula
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The feathers on the thumb of the bird's wing are called alula ( thumb wing , corner wing , also dorsal wing) . Usually there are three or four broad, firm and pointed feathers with short, powerful coils. The alula is large in those bird species that often fly with a brake, e.g. B. forest dwellers.
The task of the thumb wing is not to let the air flow over the wing be interrupted, even at a steep angle of attack , so that the dynamic lift of the wing is maintained. The Alula thus fulfills the same task as the slat on aircraft.
literature
- Wolf-Dieter Busching: Handbook of the plumage of European birds. AULA-Verlag, Wiesbaden 1997, ISBN 3-89104-570-0 .
