A fun way that I found to tame one of these:

What you need:

* an argy or PT

* some parachutes

*harpoon gun (w/net Projectile)

*tranq darts/shocking tranqs

Since these guys don't like to land, I found this strategy to be pretty affective for taming. I guess you could also wait for the quetzal to get a little too close to land, but that could take a while. Just find a quetzal, then fly a little bit over it with your flyer. (Make sure your flyer is set to follow you so it's not stuck high up in the air if you miss the first time.) Then you jump off your flyer, use a parachute to get closer, and then hit the quetzal with the net projectile. In my experience, the quetzal shouldn't take fall damage from the fall. Then all you have to do is float down to where it fell, tranq it out and tame! Easy as pie.