The best idea I've found for your first Wyvern (post bird nerf) is to build a small 2x2 stone or metal hut with a storage chest and a bed inside right next to the scar. Wait for an opening, and grab the egg. Fly up and die in front of your house. Spawn in the bed, grab the egg from you cold lifeless body, and pop it in the chest. Run outside and die again. Then wait for the wyverns to despawn (20 minutes) and retrieve the egg. In the end, you're sacrificing a tapajara for a wyvern. As for milk, I'd recommend a chain bola setup and a couple tribe mates to tranq it.

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