When using tranq arrows shoot'em anywhere but the head. 3 arrows should KO them. I was taking a level 36 ptera. I recommend using kibble as raw meat takes a lot of time and narcotics. Don't try it if you don't have a trike or anything effective at gathering.
dont send your ptera to fight another one cause they will continue to spiral upwards and fly super far in the sky, and you'll lose them. I thought I lost mine, then I found you can summon them so I got him back. He was tamed at level 150😁