Transmission of Foraging Specializations of Bottlenose Dolphins
By Jessica Weiss, MSc Student
Duke University

Bottlenose dolphins have evolved complex foraging specializations to detect and pursue prey. Individual preference plays a role in the use of foraging specializations and may be shaped in response to habitat or variation in prey resources. Foraging specializations may be products of cultural transmission, and the long duration of the mother-calf bond presents an ideal opportunity for mothers to transmit specialized foraging behaviors to their calves. Transmission of foraging specializations within a community allows individuals to adapt to environmental change and to reduce indirect competition for prey.

I am interested in the mechanisms by which foraging specializations are transmitted within the Sarasota dolphin community. Two examples of such specializations include barrier feeding and kerplunking. Dolphins may use several types of structures as barriers to herd fish. These structures may include seawalls, markers, or the water surface. Kerplunking is a behavior in which the dolphin raises its tail stock and drives its flukes through the water column, creating a splash, bubble cloud, and low frequency sound. It is believed that the purpose of this action is to elicit a startle response in fish so that the dolphin may find its prey. Such foraging specializations are correlated with particular habitat types, and I am also interested in how the use of specialized foraging behaviors affects choice of foraging habitat. During the summer of 2003, I followed five females and their dependent calves for a total of 40 hours to document which foraging specializations they used, in what types of habitats they were used, and whether calves showed indications of learning the specializations from their mothers. Data analysis is currently in progress, however, preliminary results suggest that females within Sarasota Bay exhibit preferences for foraging specializations. Further analysis will determine if females target foraging habitats to use these specializations and whether calves learn specialized foraging behaviors from their mothers. The results of this study will define future research questions concerning the stability of foraging specializations within a community and provide insight into the mechanisms of transmission of complex behaviors. Support for this project was provided by Mote Marine Laboratory, Duke Marine Laboratory, and Dolphin Biology Research Institute.