Abstract
Introduction
Over 100 years ago, McAtee (1912) set out to settle once and for all the debate on whether data on the contents of animal stomachs should be presented as percentage-by-bulk (the volume of each prey type; percentage volume or volumetric percentage) or numerically (based on counts of the number of individuals in each food type; numerical percentage). He didn’t succeed, with numerous other authors, including Pinkas et al. (1971) and Hart et al. (2002), also considering the question many years later. Indices combining multiple methods were proposed, while others argued strongly for presentation of the different methods individually to facilitate combining data across multiple studies in meta-analyses (Buckland et al. 2017). The story continues in Chapter 3, where the authors wrestle with the practical problems of identifying foods from stomach contents and quantifying the findings. The persistence of the debate confirms the ongoing interest in animal diets, acknowledging that there is still much discussion on how best to describe and quantify their important features. In this chapter we first outline the compelling reasons why it is important to study animal diets, grouping them under the themes of natural history, ecosystem function, food selection behaviour and practical applications. We then turn to the question of how to study animal diets, which is the primary focus of the book, explaining how the remaining chapters are structured to answer this question.
