The Collaborative International Dictionary of English v.0.48:

Buzzard \Buz"zard\, a.
   Senseless; stupid. [R. & Obs.] --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Buzzard \Buz"zard\ (b[u^]z"z[~e]rd), n.[O.E. busard, bosard, F.
   busard, fr. buse, L. buteo, a kind of falcon or hawk.]
   [1913 Webster]
   1. (Zool.) A bird of prey of the Hawk family, belonging to
      the genus Buteo and related genera.
      [1913 Webster]

   2. (Zool.) In the United States, a term used for the turkey
      vulture (Cathartes aura), and sometimes
      indiscriminately to any vulture.
      [PJC]

   Note: The Buteo vulgaris is the common buzzard of Europe.
         The American species (of which the most common are
         Buteo borealis, Buteo Pennsylvanicus, and Buteo
         lineatus) are usually called hen hawks. -- The
         rough-legged buzzard, or bee hawk, of Europe (Pernis
         apivorus) feeds on bees and their larv[ae], with other
         insects, and reptiles. -- The moor buzzard of Europe is
         Circus [ae]ruginosus. See Turkey buzzard, and
         Carrion buzzard.
         [1913 Webster]

   Bald buzzard, the fishhawk or osprey. See Fishhawk.
      [1913 Webster]

   2. A blockhead; a dunce.
      [1913 Webster]

            It is common, to a proverb, to call one who can not
            be taught, or who continues obstinately ignorant, a
            buzzard.                              --Goldsmith.
      [1913 Webster]

WordNet (r) 3.0 (2006):

buzzard
    n 1: a New World vulture that is common in South America and
         Central America and the southern United States [syn:
         buzzard, turkey buzzard, turkey vulture, Cathartes
         aura]
    2: the common European short-winged hawk [syn: buzzard, Buteo
       buteo]