One story is of the Thunderbird. In Native American mythology, Thunderbird is a powerful spirit in the form of a bird. Through its work, the earth was watered and vegetation grew. Lightning was believed to flash from its beak, and the beating of its wings was thought to represent the rolling of thunder.

They believed that not using up everything from an animal or plant was bad luck. This is called Animism and is based on a belief that not only humans have spirits but other things like plants, animals, and rocks also have them. Animism is just another reason that the Sioux Indians loved nature.