Ehh, to be honest i think your reading to much into this. As even Sadia knew their was something going on with the Dark Aves. What Deal they have with the quetz is still unknown. Or why are their even dark aves to begin with? Further more, if you look at their feet you see purple glowing stuff. In other words they have some kind of magic.
On the topic of the kingdom itself. Got to wonder something. What exactly is the kingdom to begin with? Think about it do the Quetz actual control any kind of land mass? Do they have any kind of territory? Further more they don't really seam to rule. Mainly just run around providing rain to people. Feels like their more of business then a kingdom.
That said, i will say this. For a small village they sure have a lot of Birds. Sadly none of them will even be useful. as i bet they are trying to swim out of this, Granted they might attract her...