Go over to extinction and tame a decent snow owl, level all in stam and heal your wyverns when they get low. It is much easier to do this when you have lots you need to raise cause you can do 3 or 4 at a time if you line them up correctly. I’m raising 20 atm and none have died. The only downside is you always have to be around healing them but once they hit adolescent you can leave them out for a hour or two. Good luck