The Collaborative International Dictionary of English v.0.48:

Birdcall \Bird"call`\, n.
   1. A sound made in imitation of the note or cry of a bird for
      the purpose of decoying the bird or its mate.
      [1913 Webster]

   2. An instrument of any kind, as a whistle, used in making
      the sound of a birdcall.
      [1913 Webster]

WordNet (r) 3.0 (2006):

birdcall
    n 1: the characteristic sound produced by a bird; "a bird will
         not learn its song unless it hears it at an early age"
         [syn: birdcall, call, birdsong, song]
    2: a device for imitating a birdcall

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "birdcall":
   Angelus, Angelus bell, alarm, alarum, animal noise, bark, barking,
   battle cry, bugle call, call, clang, cry, grunt, howl, howling,
   last post, mating call, moose call, note, rallying cry, rebel yell,
   reveille, stridulation, summons, taps, trumpet call, ululation,
   war cry, whistle, woodnote