Bird communities in flooded rice strips of different widths were surveyed in 71 fields around Lake Kasumigaura, on the Kanto Plain (central Japan). Strips categorized into four width classes (<50, 50-100, 100-300 and >300m) and two locations (core >100 and <100m from edges) were censused from May to July 1998, and mean species number and density of birds were compared. Both density and mean species differed significantly between classes, strips >300m wide favoring bird diversity and number of marsh and grassland species. Breeding skylarks and fan-tailed warblers hardly occurred in fields adjacent to edges. Strips <50m wide were not suitable feeding site of egret species (Ardeidae), but supported diurnal activity of black-crowned night herons and species requiring both rice fields and adjacent environment. As a consequence, bird conservation in rice field strips needs to consider both their width and location within the environment.