Intergroup competition in white-faced capuchin monkeys (Cebus capucinus) : automated radio-telemetry reveals how intergroup relationships shape space-use and foraging success
In social species, groups compete over access to resources, such as food, mates and water, which are critical for survival and reproduction. Competitive ability tends to increase with group size, and thus intergroup competition is thought to provide a selective pressure favoring large groups. However, this hypothesis remains largely untested because competitive interactions between groups are rare and difficult to observe. I overcame these logistical problems by using a novel technology, an Automated Radio Telemetry System (ARTS), to simultaneously monitor the movements of six neighboring white- faced capuchin (Cebus capucinus) social groups. Here, I use ARTS movement data in conjunction with behavioral observations to test the predictions that competitive ability increases with group size and large groups have greater access to resources than their small neighbors. Based on approach/avoid interactions among groups, I found that the odds of winning an intergroup interaction increased with relative group size, but that the effect was not uniform across space. Despite their competitive disadvantage, small groups were able to defeat much larger groups in the center of their home range. Behavioral observations demonstrated that capuchins did not gain immediate feeding or mating benefits from competing with neighboring groups, so I tested the prediction that subordinate social groups experienced increased travel costs or reduced foraging success compared to their dominant neighbors
Thesis, Dissertation, English, 2008