Nest boxes as microhabitats supporting diverse arthropod communities

Abstract Bird nesting boxes are widely used to support cavity‐nesting birds but also function as accessible micro‐habitats for diverse arthropod communities. This study examined the arthropods inhabiting nesting boxes across eight woodland sites in England and Wales, with a focus on how community structure is influenced by bird nesting activity and whether it impacts breeding success in Ficedula hypoleuca (European Pied Flycatcher). Arthropods were sampled from 120 boxes using modified sticky traps (in unoccupied boxes) and NaCl flotation (in occupied nests). A total of 3634 specimens from 82 arthropod families were collected. Nest boxes with bird nests supported significantly higher arthropod abundance, richness and Shannon diversity than unoccupied boxes. Despite changes in community composition between occupied and unoccupied nesting boxes, no functional groups significantly predicted or impacted breeding outcomes. These findings highlight the overlooked conservation value of nest boxes for nidicolous arthropods and call for more frequent consideration of invertebrate communities in nest box design and management.