An excerpt from Wikipedia :
In poetry from Homer, an oral tradition of the 8th or 7th century BC, onward, Athena’s most common epithet is Glaukopis (γλαυκῶπις), which usually is translated as, bright-eyed or with gleaming eyes.
The word is a combination of glaukos (γλαυκός, meaning gleaming, silvery, and later, bluish-green or gray) and ops (ὤψ, eye, or sometimes, face). It is interesting to note that glaux (γλαύξ, “little owl”) is from the same root, presumably according to some, because of the bird’s own distinctive eyes. The bird which sees well in the night is closely associated with the goddess of wisdom: in archaic images, Athena is frequently depicted with an owl (or “owl of Athena” and later under the Roman Empire, “owl of Minerva”) perched on her hand. This pairing evolved in tandem so that even today the owl is a symbol of perspicacity and erudition.
Unsurprisingly, the owl became a sort of Athenian mascot. The olive tree is likewise sacred to her. In earlier times, Athena may well have been a bird goddess, similar to the unknown goddess depicted with owls, wings, and bird talons on the Burney relief, a Mesopotamian terracotta relief of the early second millennium BC.