Project: Juvenile bottlenose dolphin social development and ecological and behavioral influences on survival in Sarasota Bay, FL

Introduction:

Photo © SDRP

The juvenile life stage is both an extremely vulnerable and formative time period for developing marine mammals. In the years between weaning and sexual maturity, juvenile animals must learn to navigate a complex ecological and social landscape in order to survive and become successful adult members of the local population. While bottlenose dolphins (Tursiops truncatus) are among the most well-studied of all cetaceans, virtually no work to date has focused on better understanding the development of bottlenose dolphin behavior through adolescence or the selection pressures acting on the juvenile life stage. Many factors remain poorly understood - for example, what are the major differences between the behavior of juvenile and adult animals? How do skills and relationships critical for adult survival and reproductive success develop through the juvenile period? What social, ecological, and behavioral factors influence survival of juvenile dolphins?

Beginning in summer 2005, I will try to begin answering some of these questions by working in the field under the direction of Randall Wells, conducting my dissertation research in conjunction with the longest-running research program on free-ranging dolphins in the world, the Sarasota Dolphin Research Program. Because of the 30+ year history of work on the bottlenose dolphin communities in the area, the “natural laboratory” of Sarasota Bay provides a unique opportunity to study juvenile dolphin behavior in a community where the animals are habituated to human presence, nearly all animals are individually identifiable, and over 90% of the resident individuals are of known age, sex, and genetic relationships.

Objective:

While the details of this project are still being worked out, the main objective is to better understand the social and behavioral development of bottlenose dolphins and to determine the major ecological and behavioral influences on survival strategies of free-ranging juvenile dolphins. To this end, I hope to address three major questions:

1) How do patterns of social behavior, activity, habitat use, and ranging develop over the course of the juvenile period from weaning to maturity?

2) What behavioral and ecological factors influence mortality/survivorship patterns of free-ranging juvenile dolphins?

3) What are the possible ecological and reproductive functions of mixed-sex subadult grouping patterns?

Photo © SDRP

Methods:

This project will combine information from the long-term datasets maintained by SDRP with new information collected through focal animal behavioral observations on current juvenile dolphins in the Sarasota community to test hypotheses regarding the critical influences on juvenile survival strategies. While I am unsure at this point whether the project will involve any telemetry methods, such as radio or satellite-tracking, we will be analyzing ranging and habitat use patterns of juveniles from sighting and follow GPS location data. By comparing and contrasting different behavioral, social, and ecological elements of the lives of juvenile dolphins, we hope to determine crucial ages at independence, better define social and behavioral maturity, and better understand patterns of mortality and survivorship of free-ranging bottlenose dolphins in Sarasota Bay.

Progress:

This project is currently in its preliminary stages, and both initial field work and analysis of long-term data will begin this summer. Stay tuned for updates as this project develops!