The Argentavis in Ark: Survival Ascended is a unique species of bird and one of the most useful creatures when tamed. You can use them to find resources, hunt, raid, transport, scout, and more. The trick is knowing where to find them on The Island.
The best place to find Argentavis is the second volcano above the redwood biome. It's safer there with fewer hostile dinosaurs and creatures to fight.
You can find Argentavis in many places on The Island, as seen in the photo above, courtesy of the Ark: Survival Evolved Fandom Wiki. You can find them:
Carno Island is the trickiest, while the redwood biome and snow biome aren't too far behind. If you're desperate, you can try your luck there.
The only way to tame Argentavis in Ark: Survival Ascended is by knocking them out and feeding them their favorite foods. Here are the Argentavis's favorite foods in order of best to worst:
Argentavis will eat the cooked counterparts of every meat and fish food item listed above, but they prefer raw meat and fish more. To tame them faster, give them raw meat and fish.
To have a more effective taming session, set up in a clear space using a Pteranodon and use a Crossbow with Tranquilizer Arrows or a Longneck Rifle with Tranquilizer Darts to knock it out.
The Argentavis is a formidable creature that can cause significant casualties to an unprepared tamer. Make sure to avoid its attacks, shoot it a few times, and when it starts to run away, follow it and shoot some more until it falls asleep. When it is knocked out, feed it its favorite food.
The Argentavis is generally easy to trap as it will have the same patterns of attack and movements towards you.
Create a small enclosure in a cleared area. Make sure the doors to your trap are too small for the Argentavis to fit through. You will need to lead the big bird in, preferably on the back of a Pteranodon, and quickly close the entrance. Try to use stone instead of wood because the Argentavis can damage wood. Knock it out and again, feed it its favorite food.