Huh, didn't know that....

So while researching what animals are sacred to which god/goddess, I found out owls are also linked to Hades. Specifically, the eagle owl. It's apparently a symbol of ill omen from the myth of Ascalaphus, where he was transformed into an owl after he told Demeter that Persephone had eaten the pomegranate seeds.

Although it seems to differ who turned him into said owl. I've read it was Demeter after Heracles released Ascalaphus from the heavy rock Demeter had crushed him under. But I also read that Persephone did it herself by sprinkling him with water from the Phlegethon.

A passage from one of Ovid's stories says this

"So he became the vilest bird; a messenger of grief; the lazy owl; sad omen to mankind."

So it seems owls are somewhat familiar with Hades as well as Athena.