Longtime symbolism include death; spiritual darkness. Related activities of the night sexual or otherwise, it therefore shares some of the same symbolism as night or moon.

It is the symbol of Athena (goddess of learning), it can relate to Wise Old Man archetypes. Some of our idioms suggest its relationship to wisdom or balancing intellect or judgement against pure emotion (wise as an owl) and to craftiness.
See birds, moon, Wise Old man.