Fictitious and Symbolic Creatures in Art, by John Vinycomb, , at sacred-texts.com
is a heraldic bird, represented as an eaglet displayed, but without beak or claws. Some writers confound it with the martlet, stating that the alerion
is the same bird with its wings displayed or extended. They are first found in the arms of Lorraine, which are blazoned or, on a bend gules, three Alerions argent, and are said to be assumed in commemoration of an extraordinary shot made by Godfrey de Boulogne, "who at one draught of his bow, shooting against David's Tower in Jerusalem, broched three feetless birds called Alerions, which the House of Lorraine,
decending from his race, continued to this day." It is impossible, says Planché, who broached this wonderful story, but it is perfectly evident that the narrator was the party who drew the longbow, and not the noble Godfrey.
The letters of the word Alerion appear to be merely an anagram formed by the same letters Loraine, and may account for the birds on the shield (probably eaglets) being called alerions.
The eagle displayed and the two-headed eagle are but extreme conventionalised representations of the natural bird.