SUMMARYNorman, F. I., L. W. Thomson and J. G. Hamilton, 1979. Use of habitat and diurnal activity of Pacific Black Duck, Chestnut Teal and Grey Teal at Serendip, Victoria. Emu 79: 54–62.The activities of Pacific Black DucksAnas superciliosa, Chestnut TealA. castanea(adults and non-flying young) and Grey TealA. gibberifronsin a fresh-water habitat and the use made of subdivisions within that habitat were studied by making hourly observations on every seventh day for ten weeks. In the study area most ducks spent the day loafing: Black Ducks fed more (28.6% of observations) than Chestnut Teal (18.3%) and Grey Teal spent little time (7.6%) feeding. Most ducks fed early and late in the day. All species shared all divisions of the habitat for feeding and loafing, the main activities considered, but Chestnut Teal used dead trees and logs more for loafing than the other species, which concentrated on isolated short grassland. Younger ducklings spent most time feeding but older ones tended to resemble adults in time spent in various activities.Any competition for food that may occur between the three species could be reduced by nocturnal dispersal to different feeding areas, by selection of different foods or by the selection of differing sizes of the same food as a consequence of the different sizes of bill.