On the Move : How and Why Animals Travel in Groups

Getting from here to there may be simple for one individual. But as any parent, scout leader, or CEO knows, herding a whole troop in one direction is a lot more complicated. Who leads the group? Who decides where the group will travel, and using what information? How do they accomplish these tasks?

On the Move addresses these questions, examining the social, cognitive, and ecological processes that underlie patterns and strategies of group travel. Chapters discuss how factors such as group size, resource distribution and availability, the costs of travel, predation, social cohesion, and cognitive skills affect how individuals as well as social groups exploit their environment. Most chapters focus on field studies of a wide range of human and nonhuman primate groups, from squirrel monkeys to Turkana pastoralists, but chapters covering group travel in hyenas, birds, dolphins, and bees provide a broad taxonomic perspective and offer new insights into comparative questions, such as whether primates are unique in their ability to coordinate group-level activities.

Chimpanzees, the human species' closest living relatives, spend their lives in serial relationships: they feed, sleep, mate, and socialize in groups whose members constantly change. Given this complex and fluid social environment, how do chimps coordinate their movements to travel as a group to, say, another feeding spot?

The question of how animals organize their group movements has long puzzled observers; even today, the mechanics of how monarch butterflies and arctic terns move from place to place are matters of considerable conjecture. In On the Move, 30 leading scholars examine that question and its implications for the study of animal communication, cognition, and memory. Some argue that carnivores and nonhuman primates lack mental representations and "game plans" for movement, relying instead on "rules of thumb" to gather information about the ground before them. Other scholars maintain that phenomena like the echolocation of dolphins and whales and the long-distance, movement-coordinating signals of elephants suggest a complex knowledge of local environments.

What is certain, the contributors seem to agree, is that "group movement is as much a social behavior as it is an ecological response to the distribution and availability of resources and risks," and therefore worthy of continued study. --Gregory McNamee