Chickens

Chickens are domestic birds that serve as food for humans: They lay eggs, and they are butchered for their meat. While docile domestic animals are rarely of interest for heroes, they serve their part in the games in a more mundane way as part of almost every farm's lifestock.

Lore
''This bird can be found on many farms. It is the source of both eggs and delicious meat often served in inns. It poses no threat to humans, as it will generally run away if attacked.''

- from "Fellowship", Ultima VII

Evolution through the Series
Their appearance in games does not change significantly. In Ultima VII, they lay eggs; In U7BG, Mack will pay you for collecting eggs.