Easy way to get a Wyvern:

Find a Wyvern trench

Get a pteranodon (high stamina 600+)

Rest on the edge and look for eggs

When your stamina is full, dart towards the egg, snatch it, and leg it towards the exit

Plop the egg down at your base and get a long ranged weapon

Go back to the trench and find some female Wyverns (or alphas)

Hit them once with your ptera and run (or just lead them away)

Land your ptera and shoot the wyvern (females have to be knocked out and alphas have to be killed)

Take the milk

If it’s female and high level, leave it so it can hatch some high level eggs for you to steal

Fly away with the wyvern milk and raise a bat on steroids:)