(Henry the Fowler). Heinrich I., King of Germany, was so called, because when the deputies announced to him his election to the throne, they found him fowling with a hawk on his fist (876, 919-936). This tradition is not mentioned by any historian before the eleventh century; but since that period numerous writers have repeated the story. He was called in Latin, Henricus Auceps.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894