A Global Comparison of Common Approaches for Tracing Carnivore Diet

Introduction Tracing consumer diet is an integral part of community ecology and various methodological approaches exist for doing so. For terrestrial carnivores, four common approaches are: (1) morphological faecal analysis; (2) molecular faecal analysis (i.e., DNA metabarcoding); (3) stable isotope analysis (SIA); and (4) GPS cluster searches. Aims and Methods Researchers often have to choose between these approaches, yet there was a lack of guidance around the strengths and weaknesses of each approach. Here, we provide that guidance by analysing data from studies that compared multiple approaches in the same system and synthesising the factors that distinguish these approaches from one another. Dietary Comparison Results Using dietary data from 64 comparisons derived from 18 papers, we found that agreement was high between morphological–molecular, low between morphological–GPS cluster and intermediate between morphological–SIA and molecular–SIA approaches. Compared to morphological, GPS clusters reported significantly less small mammals and medium mammals, while SIA reported less plants; researchers should consider their approaches carefully if their focal species eat these foods. Non‐Dietary Comparison Results These approaches also vary across other dimensions, including typical sample sizes, whether samples can be linked to individuals, the timeframe represented by the sample and cost. Indeed, per sample, morphological and SIA approaches seem to be substantially less expensive than molecular and GPS cluster. Synthesis We provide several practical recommendations that highlight the contexts where each approach is most appropriate. Ultimately, we show that there are a variety of both dietary and non‐dietary factors that researchers should consider when choosing how to trace carnivore diets.