I haven't tried with one that big but I'd assume so since you have to haul fish carcasses around for hesperonis and otter taming. Not sure I'd fancy trying to swim or walk with that beast in my hands though!

I added to my argy collection today. Saw this female flying around and had to have her. Level 130 too so not bad; she actually had better stam and weight than the ones I've bred so far.

Story of my life, except irl they don't let themselves be tamed.

On a more serious note, can you fly on the back of these giant birds?

Sure you can! They can pick up small and medium dinos too, carry lots of weight but aren't particularly fast.