Of you want to knock out a quetzal (solo).

Its easy to use a grappling hook.

You take 2 crosbows with you.

Crosbow 1 you load with THE grappling hook.

Crosbow 2 you load with tranq arrows.

If you see the quetzal you shoot it with the grappling hook (i recommand you to take more grappling hooks with you of you mis) if you hit the quetzal and your grappling hook is stuck on it you get crosbow 2 out and you shoot it with tranq arrows.

To make sure you land save take a parachute with you if the quetzal is down you switch to your parachute and land safe.