What may be one mans trash, may be another mans treasure, the have the most powerful stuff to keep creatures unconscious and there easy to kill if you know how to, use slingshot, spear, pike, all bows, guns anything that can reaching without you getting hit.
Using a quetzal, kill the ones on the surface for easy bio toxin, then use it to make shocking darts, which are better than tranq darts, or use the bio toxin as a better narcotic for being Dino's torpor up
They drop a pretty neat resource called 'Bio Toxin' when killed. It can be use as a steonger alternative to the Narcotic. It can also be used for a new 'Shocking Tranq Dart' which can shock the target and add a substantial amount of torpor. Perfect for knocking out Quetzal's.