Since the 1970s, virologists have pointed to South China as a hypothetical ‘epicenter’ of influenza pandemics. In particular, several key studies highlighted the farming practice of ‘free-grazing’ ducks (fangyang) as the crucial ecological factor driving the emergence of new flu viruses. Following the emergence of highly pathogenic avian influenza viruses in 1997 and 2004, free-grazing ducks became a primary target of biosecurity interventions from global health agencies and China’s national government. This article compares the global health ‘problematization’ of free-grazing ducks as a pandemic threat with the manner in which duck farmers around Poyang Lake, China, engage with the dangers of disease in their flocks. Showing how both global health experts and duck farmers configure the uncertainty of disease against ideal modes of ordering the relations among species, I conclude by examining how these two problematizations interact in ways that mutually intensify – rather than moderate – uncertainty.