Post provided by Jordan Cuff and Lorna Drake

The cover of our March issue shows a female Eurasian otter (Lutra lutra), with its young kit bringing a crab to shore before eating it. The photographer, Alan Seymour, had been watching the otter from a distance, while laying low behind a large boulder. Direct observations of trophic interactions take a lot of time and skill, especially concerning cryptic species (e.g., semi-aquatic mammals, small invertebrates). Accurately and precisely identifying prey items is mostly impossible by observation. Molecular methods, such as DNA metabarcoding, offer a sensitive approach for investigating trophic interactions of cryptic species; however, this high sensitivity can introduce errors. In this post, the authors discuss potential sources of errors in dietary metabarcoding datasets, and how to use minimum sequence copy thresholds to carefully remove them, detailed in their Methods in Ecology and Evolution article “An assessment of minimum sequence copy thresholds for identifying and reducing the prevalence of artefacts in dietary metabarcoding data”.