Behavioral development of free-ranging juvenile bottlenose dolphins (Tursiops truncatus) in Sarasota Bay, Florida

The juvenile life stage is both fragile and formative for young animals learning to navigate complex social and ecological environments. Bottlenose dolphins (Tursiops truncatus) are particularly interesting from this perspective as they have complex fission-fusion social systems and a prolonged developmental period, both while dependent on their mothers and as independent juveniles. During this period, they shift from associating in mixed-sex groups of young animals towards sexually segregated male alliances and female networks as adults. This project used bottlenose dolphins at a long-term study site as a model system to explore behavioral development, provide insights into the functional significance of groups, and examine the effects of environmental disturbance on the behavior of newly-independent animals.;To achieve this, I combined long-term sighting data from the resident dolphin community in Sarasota Bay, FL with new information on activity patterns, habitat use, ranging behavior, and social associations collected through focal animal behavioral observations on 27 individuals during 2005-2008. This research is one of the first studies of independent juvenile behavior in cetaceans and provides a more comprehensive understanding of behavior throughout life history for long-lived species with extended immature periods.;Chapter One provides background information on juvenile behavior, social complexity, and the study population. In Chapter Two, I examine social and behavioral development of juvenile dolphins, focusing on activity budgets and social associations. This chapter highlights individual variability in social development, sex- and age-related differences in juvenile behavior, and continued maternal influences on sociality post-independence. In Chapter Three, I explore juvenile dolphin habitat selection, ranging behavior, and natal philopatry. This chapter documents seasonal differences in behavior, changes to ranging patterns coincident with life-history transitions, and maternal transmission of ranging and habitat use patterns. Both chapters discuss findings relative to three hypothesized benefits of groups: predator protection, foraging efficiency, and socialization. Finally, in Chapter Four, I investigate how large-scale natural disturbance events, in the form of severe harmful algal blooms, affect dolphin behavior. This chapter provides evidence that red tides affect activity budgets, sociality, and ranging behavior of inshore dolphins and links these effects to underlying changes in resource availability during blooms.