WASHINGTON, Dec. 28 (UPI) -- Small monkey groups may win territorial disputes with larger groups because some members of the larger groups avoid aggressive encounters, U.S. researchers say.
Scientists working at the Smithsonian Tropical Research Institute say individual monkeys in large groups who will participate in defending their home territory often choose not to participate in conflicts in which the larger group is the invader, giving smaller groups a "home field" advantage.
Researchers used recorded vocalizations to simulate territorial invasions into the ranges of wild white-faced capuchin monkey groups at the Smithsonian research station on Barro Colorado Island in Panama.
Monkeys responded more vigorously to territorial challenges near the center of their territories and were more likely to flee in encounters near the borders, they found, and defection by members of larger groups was more common than defection by members of smaller groups.
These behavior patterns even the balance of power among groups and may explain how large and small groups are able to coexist, the researchers said.