9701063 Wethey Why animals for groups is central question in the field of sociobiology. Researchers have proposed five models to explain why social aggregations form. Three of these suggest that groups form because they help protect group members from predators. Mathematically, group membership should lower the risk of predation to each individual at the expense of its neighbors. Conversely, many experiments have demonstrated that rapid scattering of a group during a predator's attack can decrease the risk of predation by confusing the predator and allowing the prey to escape. Other work has shown that predation risk is decreased in groups because there are more sets of eyes to watch for possible danger. The other two models that explain social aggregation suggest that group formation would increase each member's ability to find food. Experiments have demonstrated that many animals are capable of watching each other's behavior and learning about good food sources from one another, and the opportunity for this would be higher in large groups than in small ones. Additionally, larger groups of animals tend to move in straighter lines than smaller groups, and it has been shown mathematically that this will lead to an increased likelihood of entering pristine, un-foraged areas. To test these five models, this study will examine group formation in burrow-building crustaceans that regularly form large flocks, and are extremely numerous in coastal marshes. Use of field experiments, direct observations, and computer analysis of video recordings, will determine which model best explains why animals form groups.
