The Goose Flamen (Druid re-skin)
by Marc Saindon"Sometime in the early 4th century BC, as the Gauls attempted to sneak into Rome under cover of night, it is said that the honking of Roman geese alerted the Romans and saved the capitol. In honour of this, the Romans later founded a temple to Juno, to whom the geese were considered sacred. Geese were also revered in the supplicia canum annual sacrifice."
Roman goose
I find the anecdote interesting enough that it can have a counterpart in Mystara, with the Thyatis geese get their own pond-park-shrine with Druidic (let's call them "Flamen" to make it sound less celtic) caretakers, although they could also be nature-aligned Clerics, with the goose serving as a holy symbol of protection, thus allowing the use of Turn Undead via bird. Yes, all of this sounds crazy, but remember, the Romans had a few weird religions.
Notes:
Flamen
(Image from: https://www.wikiart.org/en/henri-motte/sacred-geese-of-the-capitol)