A thunderbird headdress with an articulated lower jaw worn by a dancer to represent his avian ancestor. The Kwakwaka'wakw say that thunderbirds were a race of people who rolled huge boulders around in the heaven. When the rocks struck one another they created the rumble of thunder. When the birds descended to this earth the flapping or their wings created thunder and the blinking of their eyes created lightning. Once on earth they removed their thunderbird headdresses and winged capes, sending these back to the heavens. They then became founders of a human lineage. The mortal descendants thereafter used the thunderbird image to represent their ancestor. When the forehead mask is worn the dancer's face is revealed below the mask to indicate the dual bird/human persona.