In short, they're rats with wings.
Except that I've never seen the inverse called a pigeon... until now.
(Actually, I don't think I've ever seen the inverse either, now when I come to think of it... heh)
But the CUTE! First oracular slugs and now winged temple-rats... what wonders will that woman unleash next?
One thing's for sure: if Ursula Vernon makes a shirt out of that, I know where my next Graphic Smash paycheck is going...