Aerial Behavior is Not a Social Facilitator in Bottlenose Dolphins Hunting in Small Groups

Abstract

Two hypotheses that could explain the function of aerial behavior in dolphins feeding in large groups are: it is a social facilitator that establishes social bonds before or after a hunt, or it aids in capture of prey. To test which hypothesis best explains the function of aerial behavior in bottlenose dolphins ( Tursiops truncatus ) that hunt in small groups, I described the behavior of dolphins based on a set of predefined parameters, estimated occurrence of aerial behavior in groups, estimated frequency of aerial behavior per dolphin, described types of aerial behavior, and related these variables to size of group and behavioral contexts: before-feeding, feeding, after-feeding, and non-feeding. Data were collected from 111 groups. Behavioral parameters were significantly different during feeding, with dolphins moving faster and engaging in aerial behavior more often than in any other context. Aerial behavior per dolphin and occurrence of aerial behavior were highest during feeding. Results did not support the social-facilitation hypothesis. Although the aid-in-capture-of-prey hypothesis was favored, data showing a positive correlation between intake of food by individuals and aerial behavior per dolphin are required as conclusive evidence.