When using find some fish
Place your bird on the ground
Set hunt and retrieve
Use hatchet and you'll get PFM from the fish it brings back once you're done getting fish set neutral and pick up your bird.
Bola it from the sky over land and shoot ONCE with a crossbow (no headshots) then wait... if its really bloody then there’s a good chance it’s going to die but if you feel like it needs one more shot than go ahead
When I set out to tame one of these, I bring a storage or make one near the location of the bird, I put all my valuables that are on me & my flyer into storage(including the kibble) until it's knocked out. To avoid being robbed & having my things destroyed.
Bola it, then use a slingshot to body shot it. Don't head shot it; it'll die within 5 hit of the slingshot. I used a crossbow and two headshots and dead. Use fists, sling, or boomerang to knock it out. Good luck, 2 2.5x Coels should suffice for the taming.
If you see one that you want to tame walking around on land, throw a tent on top of it, and get your bola ready. It can help keep them trapped. However they can escape if you're not quick enough with the bola, also they can destroy the tent if they start to attack it. I've tamed them many times this way, so it can be done.
These things are weak so use darts since it does less damage, easiest way to knock it out is to watch it until it comes down to steal your stuff then bola it head on. Worked every time for me. Also force feeding it a little meat will keep it from dying, that's what happened with me. Hope this was helpful.