Because while it was all very well, to throw in that the dove maidens celebrate the feast of the patron saint of doves (St. David, March 1), and note casually that other bird maidens would celebrate others. . .
But the new dove maiden would find that an Educational Experience, since she's new to all of this. So the burning question is, which birds would be next.
Not something that can be finagled about, since the story's going to have to shift in time to fit (the date won't!), or shift subtly in structure.
At least it doesn't need a definitive list of all shapeshifters in this world. Just the ones so concentrated in the town that they will celebrate here, with visitors, instead of being the visitors elsewhere.
Unsurprisingly, some wild animals and wild birds don't have patron saints, or even saints that they feature in a iconography of. (Spoonbills, anyone?) I'm going to have to do some world-building.