An invasive appetite: Combining molecular and stable isotope analyses to reveal the diet of introduced house mice (Mus musculus) on a small, subtropical island

House mice (Mus musculus) pose a conservation threat on islands, where they adversely affect native species’ distributions, densities, and persistence. On Sand Island of Kuaihelani, mice recently began to depredate nesting adult mōlī (Laysan Albatross, Phoebastria immutabilis). Efforts are underway to eradicate mice from Sand Island, but knowledge of mouse diet is needed to predict ecosystem response and recovery following mouse removal. We used next-generation sequencing to identify what mice eat on Sand Island, followed by stable isotope analysis to estimate the proportions contributed by taxa to mouse diet. We collected paired fecal and hair samples from 318 mice between April 2018 to May 2019; mice were trapped approximately every eight weeks among four distinct habitat types to provide insight into temporal and spatial variation. Sand Island’s mice mainly consume arthropods, with nearly equal (but substantially smaller) contributions of C3 plants, C4 plants, and mōlī. Although seab..., House mouse metadata includes house mouse samples as rows and columns include data related to the date collected, location, and habitat type as well as the sex and age of each mouse specimen. The mouse metadata set contains data from mice captured on Sand Island from April 2018 to May 2019. We used eight existing traplines across Sand Island to capture mice and account for differences in food source composition, availability, and accessibility. Each trapline consisted of five pre-baited traps with peanut butter and oats spaced 10 m apart, for a total of 40 traps (n = 40). We trapped mice across four habitat types: forest, herbland, shrub, and wetland. We conducted seven trapping sessions; each averaged 6.1 (± 0.7 SD) trapping days (or 5.1 ± 0.7 SD trap nights), and intervals between trapping sessions averaged 55.8 (± 15.0 SD) days. For each mouse captured, we determined sex (female, male, unknown), reproductive condition (if female), and age (juvenile, adult, unknown). Mice were humanel..., For house mouse metadata: Variables include \"SIA ID\" and \"NGS ID\" (both of which identify a specific hair sample [for stable isotope analysis] and a colon sample [for next-generation sequencing]); \"Scientific Name\"; \"Order\"; \"Date Collected\" (between April 2018 to May 2019); \"Sex\" (male or female); \"Age\" (only adult); \"Trap\" (trap ID where mouse was captured); \"Trapline ID\" (trapline ID where mouse was captured); \"Habitat\" (one of four habitat types in which traplines were located: forest, herbland, shrub, wetland); \"Trapping Session\" (trapping session when mouse was captured: 1 through 7); \"Latitude\" and \"Longitude\" (coordinates of mouse capture).
For ASV data: For plant ASVs, we filtered out all ASVs assigned to any phylum other than Streptophyta (land plants and all green algae except Chlorophyta). Similarly, for arthropod ASVs, we filtered out all ASVs assigned to any phylum other than Arthropoda. For both plants and arthropods, we used only ASVs identified at least to genus in subs...