The Collaborative International Dictionary of English v.0.48:

Ornithomancy \Or*nith"o*man`cy\, n. [Gr. ?; 'o`rnis, 'o`rniqos,
   a bird + ? divination: cf. F. ornithomancie.]
   Divination by means of birds, their flight, etc.
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         Ornithomancy grew into an elaborate science. --De
                                                  Quincey.
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