The question of how to make life secure in a world of zoonotic disease threats is often answered in terms of an ever-tighter regulation of wild, domestic, and human life, as a means to control disease. Conversely, in both theoretical and practical engagements with the business of making life safe, there is recognition of the circulatory and excessive qualities of life, its ability to overflow grids of intelligibility, and a requirement for knowledge practices to be responsive to a mutable world. In this paper we use empirical work on the field and laboratory practices involved in knowing life, specifically within the UK's avian influenza wild bird survey, in order to argue strongly for a form of biosecurity that does not seek to integrate life or the practices that make it intelligible into grids and closed circuits. Extending work by Latour, we argue that the truth-value of life science not only stems from the circulation of references along a single chain of reference; it is also dependent upon the productive alliance of knowledge forms and practices that are loosely brought together in this process. By demonstrating the range of practices, materials, and movements involved in making life knowable, we claim that it is the spatial configurations of knowledge practices, organisms, and materials, their ongoing differentiation and not their integration, that make safe life a possibility.