Datasets of Bird Species Composition in a Land Reclamation Area of Lake Kahokugata, Central Japan, in Relation to Various Farmland Types.

Agricultural intensification and land reclamation have transformed natural wetlands into farmland across East Asia, which has been a threat to bird diversity, particularly wetland and grassland specialists. Despite extensive research in warm temperate and tropical rice-growing regions, bird communities in snow-rich agricultural wetland landscapes remain poorly studied. Here we present a dataset describing bird assemblages in a heterogeneous agricultural landscape surrounding Lake Kahokugata, located in a snow-rich region on the Sea of Japan side of central Japan. The area represents a land reclamation zone shaped by decades of wetland conversion. We conducted point-count surveys across 43 plots in winter and summer (2021 and 2023), yielding 129 replicated observations. The plots encompassed diverse cropland types, including rice paddies, lotus root fields, vegetable fields, pastures, and abandoned lands, representing a mosaic of wet and dry farmland. The dataset includes abundance records of 41 bird species, along with land-use attributes within a 75 m radius and landscape data on open waterbodies within a 500 m radius. Our data is useful in providing insights into how landscape heterogeneity, cropland composition, and seasonal dynamics influence bird diversity in snowy agricultural wetlands.