In the early twentieth century, ornithology underwent significant changes. So far, these changes, basically, have been studied by focussing on the elite of professional biologists working at universities or state museums. However, important developments also occurred in what Lynn Nyhart has called “the civic realm” of science – the sphere given form by private naturalist associations, nature writers, taxidermists and school teachers. This article studies the changing dynamics of civic ornithology, by looking at one particular case: the influential orinthological observatory (...) in Rossitten, East-Prussia. This observatory, the first of its kind, was founded in 1901 and led, for the first three decades of its existence, by the minister Johannes Thienemann. This article analyses the ornithological practices Thienemann developed in Rossitten and the rhetoric he used to defend these practices. In both, so it is argued, one finds a mixture of the traditional, locally anchored naturalist approach with the new ideals of the “modern” and “experimental” university laboratories. The innovations which Thienemann introduced in this hybrid form of ornithology called for specific spatial strategies which made optimal use of the natural chatacteristics of his workplace and which mobilized a large civic network of geograhically scattered amateurs. At the same time, his work also altered the space he shared with the birds – materially, conceptually and culturally. Thus, this article maintains Thienemann's ornithology can only be understood by acknowledging its continuous interaction with the geographical and civic context in which it arose. (shrink)