Between 1910 and 1915 the American Museum of Natural History carried out several expeditions in Colombian territory. Taking into account recent studies on U.S. cultural imperialism and science and imperialism, this paper analyzes the collections of birds from these expeditions to explore the role of North American imperialism in science, as well as the role of North American science in the expansion of the United States in the first decades of the twentieth century. The paper illustrates how theories of race and migration shaped the way in which North American naturalists appropriated and comprehended Colombian nature. Likewise, the paper explores the perspective of Colombian naturalists towards the expeditions, concluding that, far from being mere puppets of North American interests, Colombians used the relationship with U.S. naturalists to pursue their own agendas.