EVALUATING FACTORS INFLUENCING MALE ALLIANCE FORMATION IN TAMANEND’S BOTTLENOSE DOLPHINS (TURSIOPS EREBENNUS)

Bottlenose dolphins (Tursiops spp.) live in fission-fusion societies, meaning the composition of groups change over relatively short time periods (i.e., hours or days). However, in some populations, long-term bonds are formed between males; the reason why these male alliances form is not well understood. One leading hypothesis for male alliance formation is high dolphin population density. Preliminary analyses indicated Tamanend's bottlenose dolphins (Tursiops erebennus) in estuarine waters near Savannah, Georgia have formed male alliances. Thus, we determined population density and distribution of allied males to evaluate hypotheses of male alliance formation.  The population density of dolphins of Savannah, Georgia was 0.899 d/km², which is under the threshold of 1.0 d/km² hypothesized by Ermak et al. (2017) to lead to male alliance formation. Sightings of allied (n=4) and non-allied (n=4) male dolphins were mapped to visualize their sighting locations. Allied males were found in less complex habitats with open water, while non-allied males were found in complex habitats with smaller creek widths (p < 0.05). Previous studies have suggested that habitat complexity may deter formation of male alliances, but the waters near Savannah, Georgia have a highly complex habitat and still have male alliances, indicating additional mechanisms leading to alliance formation. It is possible that no single factor influences male alliance formation; rather, locations with or without allied males have multiple factors influencing formation of these bonds. 

Presentation Preference: Poster

Primary Presenter: Angelic Nunez, Bowdoin College (anunez@bowdoin.edu)

Authors:

Angelic Nunez, Bowdoin College  (anunez@bowdoin.edu)

Tara Cox, Savannah State University  (coxt@savannahstate.edu)

Robin Perrtree, Savannah State University  (perrtreer@savannahstate.edu)