The Vulture is a new mob added in the 'desert' update. It spawns in the desert biome. It acts like a angry hawk, flying around. However, when grounded, it will try to kill any player nearby, forever. Since it is a aggressive mob, not a neutral, it will never be 'not aggressive', then, it will forever be above a player, that is invincible. It and the hawk are the only two mobs that can fly.