Watch it's mouth. When little spurts of fire are coming out, its ready for catching, but don't go too far. If you make his ears go down, STOP ATTACKING HIM. You'll kill him within a couple hits of his ears going down, and he might fly away after you have laid your trap. That really sucks.
So just try to catch him once his ears go down, then pound him with tranq bombs (all of them, just to make sure) and he's caught.
For anyone who doesn't know, I used to be Tree Afro.
You will come to understand fear as I have...
If you were me, you'd want to be you again...