Augury

n. sign of what will happen, omen

The Augur (pl: augures) was a priest and official in the classical world, especially ancient Rome. His main role was to interpret the will of the gods by studying the flight of the birds (flying in groups/alone, what noises they make as they fly, direction of flight and what kind of birds they are), known as "taking the auspices." The ceremony and function of the augur was central to any major undertaking in Roman society--public or private--including matters of war, commerce, and religion.
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Noun
1. an event that is experienced as indicating important things to come; "he hoped it was an augury"; "it was a sign from God"
(synonym) sign, foretoken, preindication
(hypernym) experience
(hyponym) war cloud
(derivation) inaugurate, usher in, introduce

(n.)
The art or practice of foretelling events by observing the actions of birds, etc.; divination.
  

(n.)
An omen; prediction; prognostication; indication of the future; presage.
  

(n.)
A rite, ceremony, or observation of an augur.
  

Divination using bird's flight