User blog comment:ShadowRezza/Easy Wyvern/@comment-3157150-20120710112608/@comment-235771-20120712072125

@ShadowRezza's second reply - If you're up high enough, a Wyvern will spawn. It doesn't care if there are other monsters around, or if you've already beaten another Wyvern before. It. Will. Spawn, if you're on Hard Mode.