Across many construction projects, and especially infrastructure projects, efforts to mitigate potential loss of biodiversity and habitat are significant concerns, and at times politically controversial. And yet, thus far, very little research has addressed the interplay of humans and animals within construction projects. Instead those interested in the politics and ethics of human–animal relations, or animal studies, have arguably focused far more on more stable and contained sites, whether organizations like zoos, farms or laboratories, or other places like homes and parks. These largely ethnographic studies inevitably perhaps downplay the unplanned, unexpected and highly politically and ethically charged, collision of hitherto rather separate human and animal geographies. Yet it is often within such colliding spaces, where animal geographies are unexpectedly found at the heart of human projects, that we formulate our respect and response to both animals and indeed other humans. We develop an examination of such encounters, with conceptual reference to actor-network theory, and documented empirically through case studies of two infrastructure projects; the findings of our research are relevant to both construction project management and future animal studies.