This article is about the legendary creature. For the airplane control surface, see Aileron.
Avalerion or Alerion is a mythological bird. It was "rather small, yet larger than an eagle" and lived near the Hydaspes and the Indus according to European medieval geographers and bestiaries, which were possibly based on a description by Pliny. Only two of the birds were said to exist at a time. A pair of eggs was laid every 60 years; after hatching, the parents drowned themselves. Alerions have been seen in coats of arms, most often depicted as a bird with no beak and feathered stumps in place of legs or no legs at all.