You can't knock out wyverns you must have a dragon egg (Fire,Lightning and poison).You can find eggs in little wyvern nests in the world scar behind the big range of mountains to the left on your map.The wyvern nests are in on the sides. Make sure you have a good high level Arge so you can escape with an egg. As soon as you take one other wyverns will come after you so you have to go! The Arge should have at least 2000 health and 400% movement speed because the wyverns might spit fire, lighting, or poison at you. Take the egg back to your base and fly as fast as you can because the dragon will follow you until you get out of it's range. Once you have the egg at your base place it around 15 campfires because it needs to be really hot. It will take awhile to hatch so you can boost the taming speed by a lot to be quicker at the home screen and go back to the world scar and get wyvern milk from female wyverns (only wyvern babies don't eat meat). Keep feeding it milk and you have a wyvern.
I got a level 150 lightning egg and I was so excited to hatch the egg...that when I went to put the egg down I accidentally ate it instead. :( ps4 users: R2 ISN'T GONNA DROP THE EGG YOU'RE GONNA EAT IT LIKE ANY OTHER EGG. REMEMBER THIS. LOGIC BEFORE EXCITMENT.