Myers, Alyson J.

The ability of adult wild Atlantic spotted dolphins (Stenella frontalis) to
synchronize vocalizations and behaviors has been found to be a key factor in overcoming
much larger bottlenose dolphins during interspecies aggression (Cusick & Herzing,
2014). Furthermore, an adult baseline of behaviors and vocalizations during aggressive
events containing synchrony has been established (Myers, Herzing, & Bjorklund, 2017).
The present study examines juvenile aggression that contains bouts of synchrony to look
at the development of this valuable skill. Differences of duration between adult and
juvenile synchronous bouts, lag sequential analyses, frequencies of behavioral classes
depending on the age class of the aggressor-recipient dynamic, differences in the
frequencies of behavioral classes depending on the synchronous state and aggressorrecipient
dynamic, and differences in behavioral classes exhibited by adults and juveniles
during different synchronous states were analyzed. Adults, across group size, were able
to maintain physical synchrony for a longer duration. Juveniles were often in loose synchronous groups before forming into a tight synchronous group as seen in adult
synchrony. Vocal synchrony during adult aggression in terms of synchronized squawks
were longer in duration than vocal synchrony during juvenile aggression. Juveniles used
more pursuit behaviors during aggression, which indicates practice of a behavior that was
found to be the most frequently used in interspecies aggression (Volker, 2016).
Additionally, when adults were present in juvenile aggression, they used fewer
aggressive behavioral classes demonstrating self-handicapping based on their opponent.
This illustrates that there is a learning period for both vocal and physical synchrony for
juvenile dolphins and that juvenile aggression, or play-fighting, is an important aspect of
the development of these skills. This study is the first to describe juvenile synchrony in a
population of wild Atlantic spotted dolphins.

Synchrony between Atlantic spotted dolphins (Stenella frontalis) is crucial for successfully
fending off bottlenose dolphins (Tursiops truncatus) during interspecies aggression. The present study
examined synchrony in adult Atlantic spotted dolphins during aggressive encounters with bottlenose
dolphins. Across group size, aggressive behavioral events increased preceding synchrony, peaked during
synchrony, and decreased dramatically after synchrony. Although smaller groups (< 10 dolphins) became
synchronous more frequently than larger groups (> 10 dolphins), larger groups remained synchronous
longer; however, smaller groups exhibited more frequent aggressive behavioral events during synchrony,
suggesting that additional aggressive behaviors may be necessary to compensate for the small group size, whereas larger groups may be able to rely on synchrony alone. Disorganized squawk bouts synchronized as physical synchrony began, but only if coupled with escalating aggressive behaviors. The synchrony during aggressive episodes observed in adult Atlantic spotted dolphins can be used as a baseline to determine the process of the development of this critical skill in juveniles.