The concept of ‘relation’ has been central to the anthropological reworking of the nature/culture and nature/society dichotomies. However, ecology is relational in a way that has often been ignored or dismissed in contemporary socio‐cultural anthropology. This article shows that there is more to ethnoecology than an ethnocentric form of analysis representing other people's understandings of the natural world through the prejudiced lens of Western scientific classifications. Three ‘fieldwork on fieldwork’ experiments involving encounters between natural scientists and indigenous communities in Amazonian Ecuador and Southern Guyana are discussed to illustrate the heterogeneity of human knowledge, the role of expert knowledge in intercultural communication, and the need to differentiate ecological reasoning from moral reasoning.