Avalerion or alerion is a term for a heraldic bird. Historically, it referred to the regular heraldic eagle. Later[year needed] heralds used the term alerion to refer to "baby eagles" or "eaglets". To differentiate them from mature Eagles, Alerions were shown as an Eagle Displayed Inverted without a beak or claws (disarmed). To difference 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. This was later simplified in modern heraldry as an abstract winged oval.
An example is the arms of the Duchy of Lorraine (Or, on a Bend Gules, 3 Alerions Abaisé Argent). It supposedly had been inspired by the assumed arms of crusader Geoffrey de Bouillon, who supposedly killed three white eaglets with a bow and arrow when out hunting. It is far more likely to be Canting arms that are a pun based on Lorraine / Erne. (alerion is a partial anagram of Lorraine).
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. A pair of eggs was laid every 60 years; after hatching, the parents drowned themselves. The term avalerion is used on the Hereford Map near the Hydaspes and the Indus, possibly based on a description by Pliny.
The word's ultimate origin is unclear, possibly adapted from the German Adler or Adelar ("eagle"). It is found in 12th-century French as alérion and in medieval Latin as alariōnem (a large eagle-like bird).