Argument In this paper I study the engagement of German ornithologists with the Collared Dove, a bird species of Asian origin that spread massively throughout Central Europe in the 1940s and 1950s. Never before had the spread of a single species attracted so much attention from European ornithologists. Ornithologists were not only fascinated by the exotic origin of the bird, but even more so by the unprecedented rapidity of its expansion. As it is argued in the paper, the advent of the bird created an outstanding opportunity for ornithologists to study the process of biogeographic range expansion. The paper traces how knowledge on the dove's expansion took shape in the social, discursive, and material practices of a large-scale observation campaign of German ornithologists (both amateurs and academics). The paper also argues that ornithologists' observation practices have contributed to the construction of a benevolent cultural image of the Collared Dove. This sets the case of the Collared Dove apart from many recent debates in which newly arriving species have been framed as a threat to biodiversity. The paper contributes both to a historical understanding of scientific fieldwork as well as of the role of scientific knowledge in the shaping of cultural meanings of animals.