Can be knocked out and then be taken wherever needed by shooting it with a grappling hook. Take it where you want it, let it wake up, start feeding. Also can be taken into a 1x1 trap if youd like to keep it safe and in the same spot. Can fit through a door so no doors allowed.
Basically, to tame a Hesperornis, you have to kill Coelacanth and drag their corpses in front of it, bigger ones seem to give more Taming Process(further testing needed). Once you tamed it, drag more fish corpses to it and let it eat, after a certain amount of fish, it will then lay wether a golden egg or a hesperornis egg. The hesperornis egg can be cooked into oil, the golden egg, if eaten, gives your dinos 500% experience for I think 10 minutes, but will give yourself only 10%. The golden egg is also used to cook kentro kibble which is needed to kibble tame the epic yutyrannus.
Honestly it just seems like a better idea to leave them untamed, they aren't worth the hassle, especially since the otter can be tamed with one salmon while this can take like 15. And its harder to get its eggs when its tamed, meanwhile the wild ones can leave eggs scattered on shores at least once a day. I'm probably not doing it right. Do you have to feed them the fish corpses or just raw fish? And how many corpses does it need? I need these answers.
Taming tip: tame a male and female 150 giga, mate them, then trade the eggs for level 20 hesperonis.
Worst. Tame. Ever.
At least on Xbox, pressing Y to feed is near impossible, especially with a large fish. And if you are trying to tame it on land, and miss the feed with Y and drop the fish it will either A) be eaten by the hesp and give you no credit, or B) float into the air and not allow you to grab it again, even when targeting.
Solo taming a 145 spino and tried a 45 hesp while witing. Spino is almost done and I finally gave up after 3 salmon in a row floated away into orbit.