These things can be real pains, when I try to take my first egg a 180 chases me across the map, now after final killing it and full growing the wyvern it gets killed instantly by a pack of wolves! I go back to the trench and see a good level, go for it and get my amazing argy killed and loose all my stuff.
I am currently flying over to my body to try to see if I can collect it. Advice don’t get any ideas from this text
Should be in this trench close to the blue obilisk in snow. Apparently the managarmar is found also near there or just in snow areas generally. The Dinoputhecus is found in the red woods and the amargasaurus is found in the snow so far mostly in the I've Wyvern den.
When encountering a wyvern cave they will attack on sight. The best way to steel their eggs is probably with a flying dinosaur with good speed and stamina. You fly through looking for eggs and make sure they dont see you when you get one. You will get into a little bit of fights with them but not many depending on what Wyvern. Hope this helps a little bit❤️