From Nest Box to Neighborhood: Patterns of Island Biodiversity Characterized Through Edna from Little Blue Penguin (eudyptula Minor) Nest Boxes

ABSTRACT Environmental DNA (eDNA) from seabird fecal samples can provide insights into diet and the broader biodiversity of the ecosystems the birds inhabit. Seabirds like the little blue penguin (Eudyptula minor; kororā) are sensitive to changes in prey availability and habitat condition, yet their diet and foraging plasticity remain poorly resolved in some regions. We used DNA metabarcoding of the eukaryotic mitochondrial cytochrome c oxidase subunit I (COI) gene to analyze fecal samples collected from nests across eight locations in an E. minor colony on Matiu/Somes Island (Wellington Harbor, Aotearoa New Zealand) to investigate diet and bycatch DNA, and how these varied with nest location and time. We detected six marine fish species known to be components of the E. minor diet. In addition, the fecal samples contained a diverse range of nondiet eukaryotic taxa, including soil invertebrates, plants, fungi, arachnids, and other local species that reflected the surrounding microhabitat. Within this nondiet/bycatch data, community composition showed subtle temporal variation, with October samples exhibiting the highest number of unique specialist taxa (171 species) and a predominance of terrestrial‐associated groups such as Ascomycota, Arthropoda, and Basidiomycota. November samples showed intermediate unique diversity (74 specialist species), while December communities showed the lowest number of specialist taxa but an increased proportion of aquatic‐associated specialists, including Bacillariophyta and Rotifera, consistent with warmer‐season activity. Spatial differences were nonsignificant, but differences in data dispersion among sites may reflect the fine‐scale influence of local microhabitat conditions in some datasets. Collectively, our results demonstrate that, even in the absence of strong dietary signals, eDNA samples from seabird colonies can act as a valuable lens into local biodiversity and ecological processes. Thus, our findings underscore the potential of feces as so‐called “biodiversity capsules” for broad environmental monitoring, habitat assessment, and the identification of ecosystem change in coastal environments.