SUMMARYDAWSON, T.J., D. READ, E.M. RUSSELL and R.M. HERD. 1984. Seasonal variation in daily activity patterns, water relations and diet of Emus. Emu 84: 93–102.The pattern of activity of EmusDromaius novaehollandiaein western New South Wales has been examined and contrasted with that of the other large native animals in the area, Red KangaroosMegaleia rufaand EurosMacropus robustus.A detailed behavioural analysis indicated that Emus were diurnal and spent a large part of the day feeding in both summer and winter. During hot days in summer they occasionally sheltered among trees from the radiation heat load. The water requirements of adult Emus measured by tritiated water turnover do not appear high but intake may be limited by the size of the simple gut, resulting in a relatively high frequency of drinking, once per day and occasionally twice per day during hot summer conditions. The water use of chicks, especially young chicks, was much greater than that of the adults. Water losses from an incubating bird, however, were one fifth of those of adult birds in similar conditions. The Emus were omnivorous, relying on insects, seed heads, berries and succulent vegetation. The Emus successfully make their living in the arid zone very differently from the marsupials and the basis of this is discussed in relation to recent findings about their physiological adaptations.