Intellectual networks linking humanitarians in Britain, Western Australia, and New Zealand in the 1850s and 1860s operationalized the concept of native “protection” by arguing contra demographic pessimists that native peoples could survive if their adaptation was thoughtfully managed. While the population-measurement capacities of the colonial governments of Western Australia and New Zealand were still weak, missionaries pioneered the gathering of the data that enabled humanitarians to objectify natives as populations. This paper focuses on Francis Dart Fenton (in New Zealand), Florence Nightingale (in Britain), and Rosendo Salvado (in Western Australia) in the 1850s and 1860s. Their belief in the necessity of population statistics manifests the practical convergence of colonial humanitarianism with public health perspectives and with “the statistical movement” that had become influential in Britain in the 1830s. We draw attention to the materialism and environmentalism of these three quantifiers of natives, and to how native peoples were represented as governable through knowledge of their physical needs and vulnerabilities.