Alerion

To differentiate it from a decapitate (headless) eagle, the alerion has a bulb-shaped head with an eye staring towards the dexter (left-hand side) of the field.

It supposedly[weasel words] had been inspired by the assumed arms of crusader Geoffrey de Bouillon, according to a tale that he killed three white eaglets with a bow and arrow when out hunting.

Medieval bestiaries use alerion for a mythological bird described as somewhat larger than an eagle of which only a single pair was said to live at any time.

The term avalerion is used on the Hereford Map near the Hydaspes and the Indus, possibly based on a description by Pliny.

[3] The word's ultimate origin is unclear, possibly adapted from the German Adler or Adelar ("eagle").