A history of the chicken examines the bird's religious significance:
Chickens were, and still are, a sacred animal in some cultures. The prodigious and ever-watchful hen was a worldwide symbol of nurturance and fertility. Eggs hung in Egyptian temples to ensure a bountiful river flood. The lusty rooster (a.k.a. cock) was a universal signifier of virility—but also, in the ancient Persian faith of Zoroastrianism, a benign spirit that crowed at dawn to herald a turning point in the cosmic struggle between darkness and light. For the Romans, the chicken’s killer app was fortunetelling, especially during wartime. Chickens accompanied Roman armies, and their behavior was carefully observed before battle; a good appetite meant victory was likely. According to the writings of Cicero, when one contingent of birds refused to eat before a sea battle in 249 B.C., an angry consul threw them overboard. History records that he was defeated.
The Dish 