Data from: Predator-prey interactions in the Arctic: DNA-metabarcoding reveals that nestling diet of snow buntings reflects arthropod seasonality

Tundra arthropods are of considerable ecological importance as a seasonal
food source for many arctic-breeding birds. Dietary composition
and food preferences are rarely known, complicating assessments
of ecological interactions in a changing environment. In our field study,
we investigated nestling diet of snow buntings (Plectrophenax
nivalis (L., 1758)) breeding in Svalbard. We collected  faecal
samples from 8-day-old nestlings and assessed dietary composition by
DNA-metabarcoding. Simultaneously, the availability of potential
prey arthropods was measured by pitfall-trapping. Molecular analyses of
nestling faeces identified 31 arthropod taxa in the diet, whose
proportions changed throughout the brood-rearing period. Changes
in nestling diet matched varying abundances and emergence
patterns of the tundra arthropod community. Snow buntings provisioned
their offspring mainly with Diptera (true flies) based on both
presence/absence and relative read abundance of diet items. At
the beginning of the season in June, Chironomidae (non-biting midges) and
the scathophagid fly Scathophaga furcata (Say, 1823) dominated
the diet, whereas the muscid fly Spilogona dorsata (Zetterstedt, 1845)
dominated the diet later in July. When accounted for availability, muscid
flies were selected positively amongst the most often provisioned
food taxa. Our study demonstrates the ecological role of the snow
bunting as a generalist arthropod predator and highlights
DNA-metabarcoding as a non-invasive technique for diet analyses with high
taxonomical precision if sufficient DNA-sequence libraries are
available.