This paper examines how zoos decide which animals to keep, drawing on guidance produced by zoo membership organisations and in-depth interviews with zoo curators. Zoos make curatorial decisions within constraints posed by each zoo’s legacy of buildings and animals. Different versions of ‘conservation value’ inform decision-making alongside other criteria such as education value, visitor value and whether or not animals are available. We find that an international agenda to rationalise zoo collection planning in the name of environmental conservation has only partially reshaped existing practices. As a ‘bald object’ in the Latourian sense, ‘conservation’ presents a clean surface, which also means that it invites projections that attach to co...