1. The modes of diurnal and nocturnal dispersions of Emberiza fucata in the area of the high density of population in winter were observed and were compared with those of some other species of genus Emberiza.
2. The study area was a quadrat (1.2×1.6km) established on the paddy field near Kushira-Machi, southern Kyushiu. We investigated this region in February, 1975 and counted 1, 149 birds of genus Emberisa analyzed here.
3. The genus Emberiza wintering in this study region included were four species, Emberiza fucata, E. rustica, E. cioides and E. spodocephala. The species of the highest density of these emberizids was E. rustica (61.2%), the second was E. fucata (33.6%), E. cioides and E. spodocephala were only few numbers (3.4% and 1.8% respectively)
4. There were some ecological differences between E. fucata and E. rustics. E. fucata which ihanbit on the grassy patch in paddy field along the river, with small flock size (av. 1.6 birds) and small variance (v=2.26). The index of clumping of E. fucata was moderately high (I=4.00) and the index of patchiness of this species was low (2.29). On the other hand, E. rustica inhabits on the wet paddy surface in the central part of the paddy field, with large flock size (av. 9.2 birds) and very large variance (v=254.23). The index of clumping of E. rustica was very high (I=44.46) and the index of patchiness was high (12.8).
5. The communal roosting assemblages of E. fucata were found on the glassy patch in paddy field and flooded area in the river. On the latter grassy area, the assembly of roosting birds was larger than the former area. The behaviours by pair were observed near and on the roosting site.
6. It seemed that the mode of E. fucata over the paddy field in winter is the intermediate type on a gradation from E. rustica to E. cioides.