This thesis examines recent shifts in wildlife documentary by way of a detailed analysis of the genre's conception and evolution in Britain. Its title, Realizing Animals, relates to the ~ notion that the "reality" of wildlife documentary is a continually changing process, in which diversifying media technologies, the historical action of genre, and particular production institutions (in line with the uneven distribution of power to influence representations of "reality") all play a role. Realizing Animals addresses a number of inter-linked research goals. Firstly, it presents a rigorous account of the BBC's central role in the construction of wildlife documentary in Britain. It examines both how and why the BBC had such an important role in the development of this genre, and why depictions of wildlife have been so important to the BBC's evolving public service ethos. This approach emphasises the importance of linking the dynamics of genre to the actions and histories of particular institutions (such as the BBC) within a wider social space. Secondly, this thesis argues against the prevalent view that digitization, understood narrowly in terms of computer-generated imagery (CGI), is inherently destructive in its effects, severing photography and documentary's claim to the real. Instead, the effects of CGI are re-conceptualised both against the background of the histo1y of photography's origins in science and documentary, and in terms of a broader understanding of digital media in contemporary culture, which includes digital video, high-definition (HD) technologies and digital editing. Within this framework, digital media can be understood to displace (rather than destroy) wildlife documentary's claim to the real, and even to be productive in its effects (allowing the creation of previously impossible "realities"). The wildlife genre's contemporary milieu in the digital age is also analysed in terms of the rise of digital and satellite broadcasting. It is argued that the resulting shift to an increasingly global multi-channel environment (marked by both competitive and co-operative institutional relationships) is linked to the increasing divergence of the wildlife genre between, on the one hand, cheaper presenter-led series shot on digital video, and, on the other hand, hugely expensive, high-end wildlife series, some of which use CGI and HD technologies. To this end, these themes are explored in the central chapters of this thesis which each comprise one of four inter-linked case histories: the development of wildlife film in Britain, the birth of wildlife television and Attenborough's landmark series (1979-2008), the wildlife docusoap Big Cat Diary (1996) and Walking With Dinosaurs (1999). The empirical backbone of this study is formed by over forty interviews with wildlife documentary makers, extensive archival research and a short observational study of a wildlife documentary in production at the BBC. Above all, Realizing Animals sets out to show that the dynamics of genre, together with the development of new media technologies and the shifting politics of institutions, have conditioned the evolution of the wildlife genre.