To predict from an omen.

ETYM Latin Of uncertain origin: the first part of the word is perh. from Latin avis bird, and the last syllable, gur, equiv. to the Skr. gar to call, akin to Latin garrulus garrulous.
(Homonym: auger).
Prophet; soothsayer; omen.
Member of a college of Roman priests who interpreted the will of the gods from signs or “auspices” such as the flight of birds, the condition of entrails of sacrificed animals, and the direction of thunder and lightning. Their advice was sought before battle and on other important occasions. Consuls and other high officials had the right to consult the auspices themselves, and a campaign was said to be conducted “under the auspices” of the general who had consulted the gods.
(In ancient Rome) A religious official who interpreted omens to guide public policy; SYN. auspex.