Social Grouping Behaviors Of Captive Female Hippopotamus Amphibius

Levels of sociality vary depending on the costs and benefits associated with grouping behavior. Grouping species form either ephemeral aggregations due to resource availability, or structured groups based on familiarity of individuals. Because there are different costs and benefits associated with different types of groups, it is important to understand more about group structure before making predictions about specific behaviors. Female Hippopotamus amphibius are known to aggregate in the wild but the true nature of their grouping behavior is still not understood. My objective was to determine if captive female hippos form either ephemeral aggregations or social groups. Behavioral data, using continuous focal animal sampling and scan sampling, were collected on a group of nine captive female hippos housed at Disney's Animal Kingdom Theme Park. The behavioral data were used to analyze interactions between hippos, association patterns for kin and non-kin as well as familiarity, dominance hierarchy, and habitat preferences. My results support the hypothesis that hippos are forming social groups due to the attraction to particular individuals. There were more associations between kin than non-kin and also between individuals that have been together longer. Captive female hippos were also found to exhibit dominance patterns within the group. The results from this study may aid in the general understanding of hippopotamus behavior and aid in the captive management of hippos. Using my results as a starting point, research can begin looking at grouping patterns and its costs and benefits of sociality in wild hippopotamus populations.