Nest boxes as microhabitats supporting diverse arthropod communities

These datasets document arthropod communities associated with bird nesting boxes across eight woodland sites in England and Wales, and their relationship to nest occupancy and breeding performance of the European pied flycatcher (Ficedula hypoleuca). Arthropods were sampled from a total of 120 nest boxes during the breeding season. Unoccupied boxes were sampled using modified sticky traps to capture free-living arthropods, while occupied boxes were sampled using NaCl flotation to extract arthropods from nesting material. Specimens were identified to family level where possible. The arthropod dataset includes records for 3,634 individual specimens representing 82 arthropod families, with associated metadata on sampling method, nest box occupancy status, site, and box identity. Summary metrics such as abundance, family richness, Shannon diversity, and functional group classification can be derived from these data. A second dataset contains breeding data for Ficedula hypoleuca, including nest occupancy, clutch size, hatching success, fledging success, and overall breeding outcome for boxes monitored during the same sampling period. These data allow linkage between arthropod community characteristics and avian reproductive metrics at the nest-box level. Together, these datasets enable analyses of how nest box occupancy influences arthropod community structure, comparisons between occupied and unoccupied boxes, and assessments of whether variation in arthropod abundance, diversity, or functional composition is associated with bird breeding performance. The data are suitable for reuse in studies of nest box ecology, nidicolous arthropod communities, host–associate interactions, and the broader ecological consequences of artificial nesting structures.