fax +44 (0)1224 311556, email a.duncan@mluri.sari.ac.uk Large herbivores play a major role in shaping vegetation community dynamics through selective consumption of particular plants and plant communities. An understanding of the factors influencing diet selection at the level of individual bites ('bite scale') is important for prediction of the impact of herbivores on vegetation at the habitat scale. Bite-scale diet selection represents an integration of the twin goals of maximizing nutrient intake and minimizing toxin intake. Recent research with ruminants in pen-fed situations has shown that animals are able to make choices between artificial foods that maximize growth and other production variables. The role of postingestive feedback as an important mechanism for allowing animals to assess the nutritional quality of particular foods, and so select optimal diets, has been recognized in a number of recent experiments. Our understanding of the role of toxin intake minimization in diet selection decisions is more rudimentary. An important advance in the last decade has been the acknowledgement of the role of post-ingestive feedback and learning as a mechanism for avoidance of dietary toxicity. Further research is required to assess the importance of these processes in relation to free-grazing animals. The extent to which an understanding of bite-scale diet selection can be used to predict habitat utilization is not well understood. At the habitat scale additional factors such as predator avoidance, social constraints, avoidance of parasitism and microclimatic effects have an important influence on foraging decisions. Future research needs to focus on developing a quantitative understanding of such decisions at the habitat scale.Diet selection: Habitat selection: Herbivore: Post-ingestive feedback Large herbivores are major drivers of ecosystem function and dynamics in many terrestrial biomes. Through grazing, trampling, defecation and urination they affect nutrient flows, vegetation community dynamics and the responses of associated fauna. In turn, ecosystem characteristics such as composition, productivity and distribution of resources determine the nutrition of individual herbivores and the dynamics of herbivore populations. Consequently, knowledge of the foraging behaviour and habitat use of herbivores is of primary importance in determining the relationships between individual animal and population performance, and between herbivorous animals and their vegetation resources. Only through the development of this understanding can objective guidance for the sustainable management of natural resources be given.Herbivores foraging in heterogeneous environments focus their foraging pressure on particular plant communities. Thus, their impact on the vegetation is distributed across the foraging environment in a non-uniform way. A range of factors can influence the choice of habitats by large herbivores, and it is important to understand these influences in order to arrive at a predictive means of assessing how herb...