Social behavior in animals.

Two sympatric species of dolphins (Atlantic spotted dolphins, Stenella frontalis
and Atlantic bottlenose dolphins, Tursiops truncatus) have been long-term residents to
Little Bahama Bank. This study assessed whether there was a change in residence
patterns or diurnal foraging depths of bottlenose dolphins following a large emigration
event in the resident spotted dolphin community on this sandbank. Photo-identification
was used to identify individual bottlenose dolphins and compare pooled years before
(2010-2012) and after (2013-2015) the spotted dolphin emigration. The identified
community size and overall residency of the bottlenose dolphins remained similar,
although two bottlenose dolphins emigrated over deep water to the site spotted dolphins
emigrated. Bottlenose dolphins diurnally fed in shallower water but remained in the same
geographic foraging locations. Reasons remain unknown for this depth change, but
potential changes in the productivity of primary bottlenose dolphin foraging habitats or
reduction of spotted dolphins from shallower depths remain possibilities.

Atlantic spotted dolphins (Stenella frontalis) and bottlenose dolphins (Tursiops
truncatus) are two sympatric species resident to the Bahamas. The visibility of the
Bahamian water provided a unique opportunity to study spotted dolphin communication
during aggression. This study’s main focus was to decipher any similarities or differences
in the behaviors used by spotted dolphins during interspecific and intraspecific
aggression. Both similarities and differences were discovered. Biting, following, and
chasing behavioral events were used more during interspecific aggression, while the
display behavioral class was used more than the contact behavioral class during intrabut
not interspecific aggression. This study showed that spotted dolphins use more energy
intensive and risky behaviors when fighting interspecifically. This could result from
having to fight and defend females from a larger species, trying to avoid sexual
harassment from bottlenose males, or needing to use behaviors that are more overt and easily understood during interspecies communication.