This paper shows that the study of animal behaviour is a valuable aid to the improvement of the management of grazing livestock under extensive conditions. The food available to grazing animals in developing countries, and particularly in the dry season in the tropics, is often of very low quality and, in addition, is frequently available at low densities per unit area. Grazing ruminants attempt to adapt to these adverse conditions by increasing the time for which they graze each day and also by dispersing more widely. However, the time for which animals can graze may be limited by solar radiation and fly irritation in the day, and by the confining of the animals in pens at night. The adverse effects of the above limitations may be partially overcome when adapted local breeds are used. Dispersion of animals improves their ability to make use of extensive pasture and in order to encourage it, an understanding of the factors that affect it such as breed difference, social behaviour, adaptation and location of watering points and other unique environmental factors must be achieved. The paper concludes with recommendations of areas worth further research. © 1994 Certre for Tropical Veterinary Medicine.