The Collaborative International Dictionary of English v.0.48:

Hen \Hen\, n. [AS. henn, hen, h[ae]n; akin to D. hen, OHG.
   henna, G. henne, Icel. h?na, Dan. h["o]na; the fem.
   corresponding to AS. hana cock, D. haan, OHG. hano, G. hahn,
   Icel. hani, Dan. & Sw. hane. Prob. akin to L. canere to sing,
   and orig. meaning, a singer. Cf. Chanticleer.] (Zool.)
   The female of the domestic fowl; also, the female of grouse,
   pheasants, or any kind of birds; as, the heath hen; the gray
   hen.
   [1913 Webster]

   Note: Used adjectively or in combination to indicate the
         female; as, hen canary, hen eagle, hen turkey, peahen.
         [1913 Webster]

   Hen clam. (Zool.)
   (a) A clam of the Mactra, and allied genera; the sea clam
       or surf clam. See Surf clam.
   (b) A California clam of the genus Pachydesma.

   Hen driver. See Hen harrier (below).

   Hen harrier (Zool.), a hawk (Circus cyaneus), found in
      Europe and America; -- called also dove hawk, henharm,
      henharrow, hen driver, and usually, in America, marsh
      hawk. See Marsh hawk.

   Hen hawk (Zool.), one of several species of large hawks
      which capture hens; esp., the American red-tailed hawk
      (Buteo borealis), the red-shouldered hawk (Buteo
      lineatus), and the goshawk.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Hawk \Hawk\ (h[add]k), n. [OE. hauk (prob. fr. Icel.), havek,
   AS. hafoc, heafoc; akin to D. havik, OHG. habuh, G. habicht,
   Icel. haukr, Sw. h["o]k, Dan. h["o]g, prob. from the root of
   E. heave.] (Zool.)
   One of numerous species and genera of rapacious birds of the
   family Falconid[ae]. They differ from the true falcons in
   lacking the prominent tooth and notch of the bill, and in
   having shorter and less pointed wings. Many are of large size
   and grade into the eagles. Some, as the goshawk, were
   formerly trained like falcons. In a more general sense the
   word is not infrequently applied, also, to true falcons, as
   the sparrow hawk, pigeon hawk, duck hawk, and prairie hawk.
   [1913 Webster]

   Note: Among the common American species are the red-tailed
         hawk (Buteo borealis); the red-shouldered (Buteo
         lineatus); the broad-winged (Buteo Pennsylvanicus);
         the rough-legged (Archibuteo lagopus); the
         sharp-shinned (Accipiter fuscus). See Fishhawk,
         Goshawk, Marsh hawk, under Marsh, Night hawk,
         under Night.
         [1913 Webster]

   Bee hawk (Zool.), the honey buzzard.

   Eagle hawk. See under Eagle.

   Hawk eagle (Zool.), an Asiatic bird of the genus
      Spiz[ae]tus, or Limn[ae]tus, intermediate between the
      hawks and eagles. There are several species.

   Hawk fly (Zool.), a voracious fly of the family
      Asilid[ae]. See Hornet fly, under Hornet.

   Hawk moth. (Zool.) See Hawk moth, in the Vocabulary.

   Hawk owl. (Zool.)
   (a) A northern owl (Surnia ulula) of Europe and America. It
       flies by day, and in some respects resembles the hawks.
   (b) An owl of India (Ninox scutellatus).

   Hawk's bill (Horology), the pawl for the rack, in the
      striking mechanism of a clock.
      [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):

Buteo lineatus
    n 1: North American hawk with reddish brown shoulders [syn:
         red-shouldered hawk, Buteo lineatus]