William L. Romey, Ph.D.
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Research Interests in Grouping Behavior:

The function and mechanisms of animal grouping are still a relative mystery in the animal world. Recent articles in Science and National Geographic summarize the work of scientists on how the actions of individuals can lead to the coordinated behavior of large schools of fish and flocks of birds. Animals form groups in order to avoid predators, gather food, thermoregulate, and take advantage of the currents created by those in front of it. However, little is known whether, or how, individuals choose specific locations within these large groups.

The decision rules that animals use to group can be studied by making computer simulation models and comparing the results with real groups. My students and I constructed such a model (Romey 1996) in which the speed, momentum, random movement, and directed motion of individuals could be controlled independently. Then we investigated the role that different strategies played in the overall movement and dynamics of the group as a whole.

Recent work with my students has focused on how individuals in a group choose locations within that group non-randomly. We have found that individuals act to optimize their position within a group based on a number of criteria. For example, if the edge of the group is the best place to find food but the center is the best place to avoid predators, we found that hungry animals would go to the edge and well-fed ones would go to the middle (Romey 1995). These experiments were done with individually marked insects (whirligig beetles) that swim at the surface of the water while being videotaped from above. We also found that males and females choose different locations within groups because of their different predator avoidance needs (Romey and Wallace 2007). And in species which swim constantly against a current, drafting (catching the wake of those in front to save energy) plays a role in where they choose to swim, along with hunger and gender (Romey et al. 2008). Our results have shown a higher level of sophistication in how animals choose positions within groups. These findings with insects suggest that “higher” animals like fish and birds may also have similar optimization rules. These rules discovered in whirligigs may also be incorporated into future simulation models which predict the collective behaviors of schools, flocks, and herds. There is also interest in this research by applied scientists such as engineers who would like to be able to make groups of interactive robot sensors that would be free-moving in the sea or space.

(see publications page of this website for references).



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