Why is Rhiannon sometimes called "Rhiannon-of-the-Birds"?

Answer 1

Rhiannon is associated with otherworldly brids, the adar Rhiannon which are explicitly named in the Mabinogion of Branwen ferch Llŷr.

Answer 2

There's an old English legend( almost like a myth) that speaks of Rhiannon. She was the goddess of the moon and magic, she was "seen" riding a white horse in the woods. Her sacred animal was a raven, or other birds.

Answer 3

I didn't know that. I love Stevie Nicks and her famous song "Rhiannon".She has always written mystical songs. So cool......That's probably where her inspiration came from.