Integration of a social cluster of Atlantic spotted dolphins (Stenella frontalis) after a large immigration event in 2013

Demographic changes can result in alterations of social structure and behavior which in turn may affect survival, reproduction, or movement and may influence how populations respond to changes in the environment. In 2013, 52 Atlantic spotted dolphins (Stenella frontalis) left Little Bahama Bank (LBB) and immigrated into a resident group of spotted dolphins on Great Bahama Bank (GBB). Initially there was little interaction and two distinct social clusters delineated by residency status. Here we describe the social structure of the dolphins on GBB between 2015–2020. Analyses were conducted with SOCPROG 2.9 and coefficients of association were nonrandom. The number of associations between LBB and GBB individuals increased, and standardized lagged association rates indicated continued associations over time. Modularity analysis showed one community without clear social clusters, although there were preferential associations within the original communities. Multiple Regression Quadratic Assignment Procedure indicated that sex, age, and residency status were good predictor variables that explained the patterns of the association indices. Male alliances were present between LBB, GBB, and LBB/GBB males. New and old relationships are influencing the social restructuring of this community. This study furthers our understanding of how demographic changes can shape the social structure of a population.