Sanderlings Feed on a Diverse Spectrum of Prey Worldwide but Primarily Rely on Brown Shrimp in the Wadden Sea

Abstract

Knowing what birds eat is fundamental to understand the ecology and distribution of individuals and populations. Often, diet is assessed based on field observations and excrement analyses, which has previously been the case for Sanderling Calidris alba. This may have biased their known diets towards large prey with indigestible body parts that can still be recognized in faeces or regurgitations. A literature review of Sanderling diet worldwide showed that Sanderlings exploit a large diversity of prey. We carried out DNA metabarcoding on Sanderling faeces to get a complete view of their diet in the Wadden Sea during staging and moult from late July to early October. Given the diversity of available prey in the Wadden Sea, it was remarkable that 94% of the samples contained Brown Shrimp Crangon crangon which, next to the Shore Crab Carcinus maenas, were also the most abundant species in the samples. This study shows that whereas Sanderling can feed on a large variety of invertebrates, in the Wadden Sea during southward staging they primarily rely on Brown Shrimp