The Collaborative International Dictionary of English v.0.48:

butcher bird \butcher bird\, butcher-bird \butcher-bird\,
butcherbird \butcherbird\n.
   1. (Zool.) any species of shrike of the genus Lanius, so
      called because they impale their prey on thorns.
      [1913 Webster + WordNet 1.5]

   2. (Zool.) large carnivorous Australian bird with the
      shrikelike habit of impaling prey on thorns.
      [WordNet 1.5]

   Note: The Lanius excubitor is the common butcher bird of
         Europe. In England, the bearded tit is sometimes called
         the lesser butcher bird. The American species are
         Lanius borealis, or northern butcher bird, and
         Lanius Ludovicianus or loggerhead shrike. The name
         butcher bird is derived from its habit of suspending
         its prey impaled upon thorns, after killing it.
         [1913 Webster]

WordNet (r) 3.0 (2006):

loggerhead shrike
    n 1: a common shrike of southeastern United States having black
         bands around the eyes [syn: loggerhead shrike, Lanius
         lucovicianus]