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.
Similarly to real life, these greedy douchebags will try to steal your sandwiches, however if you are drunk enough, you can stay up into the late hours of the evening and have deep insightful conversations with these feathered friends as they simply stare at you in confusion and bark in bird language. In return they will bring you magical fish as a reward.
You have to tame a high level because it would have so little health you would kill it by accident. I would use a long neck to knock it out and probably 10 bolas because they are pretty hard to hit. Up if this helped.
They need to make it so that if you put narcos bio toxin etc in ur last hot bar a lot the icthyornis will eat them and get knocked out(like putting berries in ur last hotbar slot to tame the pego, but instead of taming it will be knocked out)
These annoying flyers can be used to aid in taming otters. Just set the hunt and retrieve feature on it, make it attack a fish, and as it comes back to you grab the fish and walk up to the otter and press the button to tame. Otters are quick tames, and provide insulation from both the heat and cold which directly depends on their melee stat. They can also hold multiple artifacts in their inventory. Can be found in shallow rivers.