The Collaborative International Dictionary of English v.0.48:

Eyas \Ey`as\, n. [F.niais fresh from the nest, a derivative fr.
   L. nidus nest. E. an eyas for a nias. See Nest, and cf.
   Nias, Jashawk.] (Zo["o]l.)
   A nesting or unfledged bird; in falconry, a young hawk from
   the nest, not able to prey for itself. --Shak J. H. Walsh
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Eyas \Ey"as\, a.
   Unfledged, or newly fledged. [Obs.]
   [1913 Webster]

         Like eyas hawk up mounts unto the skies,
         His newly budded pinions to assay.       --Spebser.
   [1913 Webster]

WordNet (r) 3.0 (2006):

eyas
    n 1: an unfledged or nestling hawk