The nestling diet of Svalbard snow buntings identified by DNA metabarcoding

Abstract

Tundra arthropods have considerable ecological importance as a food source for several bird species that are reproducing in the Arctic. The actual arthropod taxa comprising the chick diet are however rarely known, complicating assessments of ecological interactions. In this study, I identified the nestling diet of Svalbard snow bunting (Plectrophenax nivalis) for the first time. Faecal samples of snow bunting chicks were collected in Adventdalen, Svalbard in the breeding season 2018 and analysed via DNA metabarcoding. Simultaneously, the availability of prey arthropods was measured via pitfall trapping. The occurrence of 32 identified prey taxa in the nestling diet changed according to varying abundances and emergence patterns within the tundra arthropod community: Snow buntings provisioned their offspring mainly with the most abundant prey items which were in the early season different Chironomidae (Diptera) taxa and Scathophaga furcata (Diptera: Scathophagidae), followed by Spilogona dorsata (Diptera: Muscidae). An influence of breeding location on the diet could not be established, although tundra habitat explained significant differences in the trapped arthropod compositions. A selectivity analysis revealed a selection towards larger sized prey taxa, which could have implications for observed variations in snow bunting nestling success. This one year study shows the promising results of DNA metabarcoding as a non-invasive technique to assess diet variations and trophic interactions.