This paper draws on Annemarie Mol's empirical philosophy as a way of handling the science of avian influenza in South Africa's ostrich industry. This is an agricultural industry in rural South Africa that has recently suffered severely from infections of highly pathogenic avian influenza. The paper draws on the ‘materials and methods’ section of scientific papers, and interviews with scientists, veterinarians and ostrich farmers, to argue that the practices associated with the disease enact multiple avian influenzas. The paper describes these different avian influenza realities and how they relate. Finally, I examine the relationship between multiplicity and policy.