Alectomancy
Alectomancy (Greek aléktōr, rooster) is divination using a rooster that pecks grains placed on letters of the alphabet, forming words interpreted as oracular answers. Practice attested in ancient Greece and Rome, recorded by writers such as Pliny the Elder.
Famous case
The Emperor Valens (4th century AD) is said to have used alectomancy to try to discover the name of his successor — case that ended in massacre of suspects.