The Thunderbird is a common mythological being known to all the tribal groups of the Northwest Coast. Physically, Thunderbirds are supposed to be of gigantic proportions. The clapping of their wings is the sound of thunder, while the glint in their massive eyes translates as flashes of lightning. So large and powerful are the Thunderbirds that it is said they routinely plunge into the ocean to seize whales, much like an eagle would prey on a small fish.
I chose to call this mask Thunderbird Spirit because, to me, Thunderbird is a spirit, or rather a force of nature, as opposed to a large bird of prey. With characteristic piercing eyes and crisp brow line, the birdlike suggestion is complemented by feather decorations painted on the face and a crown of real feathers. Like all spirit masks, the nose has a distinct hook, a beak-like shape with human nostrils. I felt that by keeping the face in human form and adding long hair and operculum shell teeth, the mask might ultimately allude to the true creators of this majestic being. Thunderbirds, you see, do exist in the hearts and imaginations of those who are still in awe of nature.
—from Spirit Faces: Contemporary Masks of the Northwest Coast, page 48.