Use an itchthyornis to gather fish for it. The buff increases efficiency.

Tame to this kill fish and drag there body to it and once tamed if you feed them more dead fish corpses it will build up and lay a golden egg which is used as a buff to certain dinos or oil or a player buff

Feeding them sabertooth salmon seems to work the best.

Taming an ichthyornis will allow you to gather the corpse by setting it on hunt and retrieve, after the fish is killed it will deliver the corpse right to you and you can tame the Hesperornis

Use a horse to lasso it, then you can move it around to new fish spawns when the area gets cleared. The horse can also step on the duck to pin it down, or simply use the lasso to keep it close while tribemates gather fish.

Can't be picked up by anything while they are wild. They do aggro on you, and can walk through door frames, so you can kite them to a taming pen then use an itchy to bring those succulent salmon to you. Tamed a 140 last night in about 20 minutes.

Lasso, drag onto a trap boat, then ride around to the fish. Bigger the fish, faster the tame.

I picked it up with a grappling hook, then jumped on my wyvern & flew it to a safer place to tame with lots of salmon. I also threw a tent over it to stop it from wandering off. Best way to tame. So much easier.

Feeding them sabertooth salmon seems to work the best.

If you insist on taming one without an Ichthythornis, a good thing to be aware of is that the Hesperonis will sometimes be unable to eat a fish it kills, swimming back and forth to try and "find" it.
You can pick up a fish it's killed and feed it to it, and it counts for tame progress.
Also be aware that if you drop a fish you've killed, it can eat your fish off the floor and it will not give tame progress.

One of the worst things you need to tame for kibble, but this is how to do it:
1. Craft a wooden cage
2. Aggro it onto land
3. Place cage on top of it
4. Spend an hour killing fish and dragging them to it, feeding it through the bars carefully or you’ll open the cage and let it out.
5. You let it out, didn’t you? Pick the cage up and trap it again.
6. Watch out for that ichth- It stoke your fish... and half the stuff in your inventory. Kill it.
7. Cuss in frustration at every piranha on the Ark trying to eat you, then feed them to it too.
8. Finally finish taming the dumb bird - now just remember to keep feeding it fish forever.

Oh and watch out for Argentavis in the area, they like corpses and they don’t like you even if you’re carrying the corpse. They’ll steal your fish and then try to kill you.

Can’t tame in snow cave on extinction.

The best way to tame it is to get fishes from a Ichtyornis. Salmons are the best.

Tame a icthycornis and make it grab a fish it works way better in fact that is the correct way to do it or intended

Breeding seems to take about 28 hours.3.5hr egg 3hr baby.

You will need to bring an icthy to kill fish and bring them to u then feed it but don't get to close, the agro.

Use an otter or itchyothornis to collect fish for you then go to the hesperornis and feed it the collected fish. They love sabertooth salmon so target those.

Use a seagull to gather the fish you need for it!! Just get your seagull to kill the fish and bring it to you, then you feed the duck

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.

To get fertilized eggs, they must be on wandering in water. They wouldnt mate onland, only when I put them in water. Just attach them to a hitching post in the water.