UCB Moorea Class: Biology and Geomorphology of Tropical Islands

Social structure is key to a species' biology and ecology. Relations within a population can have important ftness consequences, but only recently have researchers been able to explicitly measure and quantify these relationships through network modeling. Social network analysis is the study of social groups as networks of nodes connected by social ties. In this study, network analysis is implemented to determine that there is a social structure within an aggregation of Himantura fai at feeding excursion sites. An ethogram defning H. fai behaviors is compiled. A sum of interactions network is subdivided into fve behavior networks to allow for further quantifcation of the relations within the aggregation. Size, color, and sex are found to be correlated to dominance, and an order of dominance is determined, with large females at the top and the smaller of both sexes at the bottom. To address the confounding factor of human presence at the study sites, the effects of feeding excursions on H. fai behavior are investigated. The variation and frequency of interactions between individuals increase with the presence of a feeder, but the amount of time spent interacting with at least one other individual is unaffected by human presence. Overall, this study investigates the effects of feeding excursions on H. fai behavior and utilizes a relatively new analytical tool to determine the social structure of H. fai.