User with this ability either is or can transform into a Thunderbird, a vast bird capable of creating storms and thundering while it flies: clouds are pulled together by its wing-beats, the sound of thunder made by its wings clapping and lightning the light flashing from its eyes when it blinks. Depending on the people telling the story, the thunderbird is either a singular entity or a species. In both cases, it is intelligent, powerful, and wrathful. All agree one should go out of one's way to keep from getting the thunderbirds angry.