Year of Publication

Spring 2016

Season of Publication

Spring

Degree Type

Honors Thesis

College

College of Arts and Sciences

Department

Biology

Degree Name

Honors in the Major

First Advisor

Dr. Quincy Gibson

Second Advisor

Dr. Cliff Ross

Abstract

Bottlenose dolphins (Tursiops truncatus) have a sexually segregated fission-fusion society, in which males and females form different types of social groups for different purposes. Social interactions among dolphins are frequent, and group composition changes just as often. Male-male association patterns reveal the formation of alliances, which range in complexity. Recently, second-order alliance formation was confirmed in the St. Johns River, but the function of these alliances is unknown. To investigate their function, this research analyzes the seasonality of first and second-order alliance formation, and whether female presence plays a role. It was hypothesized that higher level male alliances form in order to improve mating opportunities in a society dominated by male-male competition. It follows then that more male alliances will form during the breeding season, including second-order alliances, and alliances of both levels will form more often in the presence of females. By analyzing boat-based photo-identification survey data, it was found that the average number of alliances was 1.5 per group in all seasons, if there was at least one alliance present. More alliances were sighted in groups with females, and this trend followed for the second-order alliances. The percent of sightings with first-order alliances was higher in the breeding season as expected. However, most of the second-order alliances were sighted in the non-breeding season, which correlates with increased aggression in the non-breeding season. This suggests that second-order alliances may be integral in establishing male dominance prior to the start of the breeding season.

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