Defaunation is one of the most critical challenges faced by contemporary hunter-gatherers worldwide. In the present chapter we explore how this global anthropogenic phenomenon is being explained by a hunter-gatherer society: the Tsimane’ of Bolivian Amazonia. First, we briefly review the historical context of contemporary Tsimane’, with a special focus on defaunation trends in their territory. We then draw on ethnographic accounts to understand how this society explains the drivers of defaunation and integrates them in their understanding of the world, and specifically in their mythology. The Tsimane’ perceive widespread defaunation in their territory, which they tend to largely interpret as a result of both natural and supernatural forces, with intertwined arguments. The Tsimane’ think that supernatural deities control animals and, consequently, they largely associate wildlife scarcity with punishments by the spirits in response to disrespectful conducts. As such, defaunation is interpreted as a consequence of (a) direct harm to wildlife populations by the inappropriate hunting and fishing behaviour; and (b) the discontentment of the animal deities for not respecting certain established cultural norms. In the Tsimane’ view, the latter is also aggravated by their recent relative inability to communicate with the spirits, due to the disappearance of shamans. Considering that the way people interpret environmental change can determine their behaviour towards proposed conservation actions, understanding the symbolic dimensions of defaunation is of direct relevance to any initiative aiming for sustainable wildlife management in areas inhabited by hunter-gatherers.