Shelterbelts support edge birds but limit grassland and wetland specialists in agricultural landscape

To mitigate farmland bird declines due to agricultural intensification, agri-environmental schemes promote the retention and plantation of woody field margins and farmland trees. While woody structures can benefit woodland and edge species, they may negatively affect open-habitat species by fragmenting habitats and increasing predation risk. These potential trade-offs remain untested in agricultural wetlands. We examined how shelterbelts influence bird species richness and abundance of each habitat group (based on life history) in agricultural wetland landscapes of Japan. By analysing bird community data collected in an agricultural wetland (rice and lotus fields) landscape in central Japan, we show higher species richness of bush/edge species in shelterbelt sites. In contrast, grassland and wetland bird species were more diverse in open habitats. After accounting for season and land use, we found a higher bird abundance of bush/edge species overall in shelterbelt sites. However, grassland species abundance was lower in shelterbelt sites, which was about 74 % lower at sites adjacent to shelterbelts (0 m) compared with those located ∼1 km away. While shelterbelts support bush- and edge-associated species, they may restrict the presence of grassland (e.g., skylarks) and wetland birds (e.g., lapwings) by reducing effective open habitats and increasing edge environments that promote predator activity, disadvantaging these ground-nesting species. Since the study area is a key stopover along the East Asian-Australasian Flyway for migratory birds, we suggest maintaining open areas within agricultural wetlands and designing shelterbelt layouts that reconcile the habitat needs of both open-area and edge-associated species.