Abstract: What are the benefits that animals gain from living in a social group? This question has been the primary focus of the author's ecological interest. After many years of original and innovative research on the African buffalo, particularly at Lake Manyara in northern Tanzania, Herbert Prins has now summarized the results of much of this widely-respected work in this fascinating book. While advantages in reduction of the risks of predation or in increased efficiency of foraging on certain types of resources are now widely recognized, until now there has been less attention paid to the idea of the animals themselves as `information centres' and the extent to which the individual may be able to make use of information gathered by conspecifics, adjusting its own behaviour in response. Such a case-study has wide implications for research on social structure and organization in other species, and these are explored within the book. However, it is not a book aimed simply at the academic researcher, zoologist and behavioural ecologist; since it is written in a readable and accessible style, the book will also be enjoyed by wildlife enthusiasts, interested naturalists, wildlife biologists and wildlife managers.

Abstract: Animal behaviour is often a function of the animal's physiological state. Groups of animals will often contain individuals with a range of physiological states and the grazing behaviour of herbivores is affected by their physiological state. This study compared the grazing decisions of animals in groups of single and mixed physiological states. Using a grazing model that simulated individual herbivore behaviour in relation to environmental distributions of forage resource (grass) and parasites (faeces), we tested the hypothesis that an animal's level of parasite exposure via the faecal-oral route is affected by the composition of physiological states in the group. Four physiological states were considered: parasite-naïve, parasitized, lactating and parasite-immune animals. Baseline parasite exposure levels for each state were generated by simulating single-state groups and were compared to simulations of each of the six two-state combinations. In single-state groups parasitized animals had the least and lactating animals had the greatest levels of parasite exposure. When co-grazing with lactating animals, parasitized, immune and naïve animals increased their parasite exposure, relative to single-state groups. When co-grazing with parasitized animals, lactating, immune and naïve animals reduced their parasite exposure, relative to single-state groups. There was no difference in parasite exposure of the immune or naïve animals co-grazing together when compared to the single-state groups. These results highlight the need to recognize the impact of the individual when studying group-living animals.