A new method of transcribing visually-recorded behavioural data rapid computer processing ; it is applied to a total of 31 animals (bulls, cows and calves) in the Markham Valley, Papua New Guinea. There is no evidence of seasonal variation. Approximately one-third of grazing is carried out at night, so that night yarding is not indicated without further investigation. Total times spent in recorded activities are comparable with those for temperate climates. There is evidence for an effect of breed, in that animals with more than half-shorthorn ancestry show a marked reduction in mid-day grazing.