Use 8 stone behemoth gateways and 2 gates to trap female wyverns for wyvern milk to feed your kidnapped wyvern. You can use tranq darts and a longneck rifle to knockout the wyvern. Use a pterodon that can outrun the wyvern or use a desmos bat at night because of its ability to camouflage to get the egg. Desmos bat is only on fjordur.