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.
I’m a lvl 84 and I’ve only seen these guys about 7 times. I was on my Argy, higher than the tallest redwood tree and I seen them. Yes they like to fly high and they have been watching you tame that lvl 45 dilo.