Okay so if you want to find easy an easy quetz or two just go to the area directly south of red obelisk around the little islands and the base of the obelisk. Two of them spawned at once from me one time.
So... I figured out the exact spots for the spawns 👍 The primary spot is just behind the red obelisk on the thin little strip of land near the southern island. (I almost always see one spawn there) I also find them frequently spawning around the “back spike” of the red obelisk. You will almost always find a quetz around these two places. (At least on mobile) If you want a high level, just kill the one that spawns at these two places and a new one will always respawn back at those two places. This technique worked for me.