Ive heard/saw on youtube that you can just jump off your argentavis or any other of your tamed flying dinosaurs and land on the wing of thw wild quetzel. make sure your bird is following you to. You can then just shoot it in the head till it knocks out. Make sure you have a parachute with you just in case you miss the bird.
The fun way is to jump off and grapple to your argie and whistle it to attack and since argies are slow it won’t catch up in time so tranq till it goes out also bring parachutes and consider liking so more people will know
Use a netgun when it flies above ground. Once netted, either have a trap ready for high levels or shoot tranq arrows into their eyes(more dmg). It you have a buddy, have them shoot with tranq darts while you shoot into the eyes with arrows. Be careful though as they’re kinda wimpy at times. Super hard to tame while solo without a net gun.
If you drop a quetzal due to knockout, and it lands next to a giga...just know, the quetzal belong to the giga. Now you get to watch your would be quetzal get eaten by a giga. Now you can go home and cry.
You can net a quetzal but before you do clear the area of any hazards and hop on you creature and bet it (Make sure you don’t shoot it when it is asleep because when is has the bet on it looks like it’s asleep)
If you manage to knock a quetzal out, try starve taming. If you never tried starve taming it’s just leaving a Dino’s hunger go to half way or lower and then you start feeding. I’ve done this many times and it’s very useful taming trick.