This paper investigates the cultural grounding of animal idioms describing human behavior in Upper Tanana Athabascan. Semantically, one can identify two types of idioms. Type I idioms are grounded in observations of real-life animals. They are iconic in that they are based on, and evoke, rich images. Type II idioms are grounded in mythology. Certain animals are cultural symbols, representing a particular trait. Type II idioms are thus symbolic. Comparison with other Alaskan Athabascan languages demonstrates that such idioms are common, but also that they are extremely endangered since they are part of the colloquial, rather than formal, language.