No idea why people want to whistle their flyers to attack the quetzal when you can literally just go as close as you can to the quetzal you wanna tame on a tapejara and then hop in a passenger seat and whistle it to follow you. This way it will literally just hover in the air and you can tranq the quetzal from there. If it goes out of range just jump in the rider seat and move closer. Keep doing this until you knock it out.

You can still use the methods where you’ll set a flyer to attack the quetzal, grapple it (or tapejara passenger) and then tranq it but if the quetzal isn’t a high enough level that method might get risky due to hp and torpor stuff. It still works just fine but my method completely avoids unnecessary damage to the quetzal so it may be safer.

Good luck, survivor!