Abstract
Two segments of rice fields (0.4 ha each) in the coastal rice-producing region of Lake Kasumigaura, central Japan, were experimentally flooded from December to February (non-cultivation season), and bird abundance and macroinvertebrate availability in the fields were compared with those in unflooded rice fields and continuously flooded lotus fields. No waterbirds were recorded in the unflooded fields, but the experimentally flooded fields attracted Northern Lapwing Vanellus vanellus and snipe Gallinago spp., probably due to higher numbers of Tubificidae, Insecta (except Chironomidae) and Hirudinoidea in the soil and the water on the fields. Snipe were more abundant in unplowed flooded fields than plowed ones, indicating the importance of leaving rice stubble and post-harvest shoots as shelter for these secretive foragers. The flooded rice fields did not attract fish-eating waterbirds such as egrets Egretta spp., herons Ardea spp. or kingfishers Alcedo atthis, which occasionally appeared in the lotus fields. This was, probably because water pumped on to the experimentally flooded fields provided few fish or tadpoles. Landbird abundance also differed significantly among the field types. Unflooded fields supported more Skylarks Alauda arvensis and Siberian Meadow Buntings Emberiza cioides than others, whereas flooded fields were preferred by Water Pipits Anthus spinoletta. Lotus fields attracted Dusky Thrushes Turdus naumanni, White Wagtails Motacilla alba and Japanese Wagtails M. grandis. The results indicate that flooding fields in a dry rice-producing region in winter provides many water- and landbird species with suitable habitats, and contributes to increasing the diversity of the wintering bird community.
