Long‐term social structure of a resident community of Atlantic spotted dolphins, Stenella Frontalis, in the Bahamas 1991–2002

Abstract

Long‐term social structure data on small delphinids is lacking for most species except the bottlenose dolphin. This study describes the long‐term social structure of one community of Atlantic spotted dolphins, Stenella frontalis, divided into three social clusters. Data from 12 yr were analyzed using SOCPROG 2.3. Coefficients of association (CoA) were calculated using the half‐weight index. The overall mean community CoA ranged from 0.09 to 0.12. Temporal analyses and mantel tests revealed significant differences between sex class associations due to high male‐male CoA (0.12–0.23) compared to female‐female and mixed sex CoA (0.08–0.10). Female associations were strongly influenced by reproductive status, calf care, and social familiarity, but not by age class. Male associations were strongly influenced by age, access to females, and alliance formation. Males showed two levels of alliance formation, long‐term first order pairs/trios (CoA 0.70–1.00) and shorter‐term second order alliances between two or more first order alliances (CoA 0.45–0.69), and a possible third level during interspecies interactions. Mating strategies, sex, and cluster formation shaped the social structure in this spotted dolphin community. Similar to many bottlenose dolphin studies, long‐term affiliations for spotted dolphins were correlated with age, sex, and reproductive status.

Pectoral fin contact as a mechanism for social bonding among dolphins

“…The lack of evidence for consistent dominance hierarchies could be related to sample size. That is, multi-year, detailed, lengthy observations of inter-individual interactions are available only from a few wild study populations (e.g., Connor & Krützen, 2015;Dudzinski et al, 2009;Elliser & Herzing, 2014;Kogi et al, 2004;Wells et al, 1987). Assuming dolphin social structure includes some level of dominance hierarchy, specific tactile affiliative behavior(s) might function as a tool to mitigate interactions to reinforce the relationship status among individuals in a group.…”

“…In several dolphin groups studied, it would seem that samesex, same-aged pairings represent the primary framework for the fission-fusion society with mixed-sex associations happening, but not as frequently; for example, Atlantic spotted dolphins, Stenella frontalis, in The Bahamas (Dudzinski, 1996;Elliser & Herzing, 2014;Herzing, 1997;Herzing & Brunnick, 1997); Indo-Pacific bottlenose dolphins, Tursiops aduncus, around Mikura (Kogi, Hishi, Imamura, Iwatani, & Dudzinski, 2004) and in Australia (Connor, 1992;; common bottlenose dolphins, T. truncatus, in the USA (Wells, 1991;Wells, Scott, & Irvine, 1987) and in The Bahamas (Rossbach & Herzing, 1999). Social tactile contact can be affiliative or agonistic (e.g., Connor, Mann, & Watson-Capps, 2006;Dudzinski, 1996Dudzinski, , 1998, and previous research suggests that at least some dolphins have preferred partners with whom they exchange contact (e.g., Connor et al, 1992;Connor, Smolker, & Bedjer, 2006;Dudzinski, 1998;Herzing & Brunnick, 1997).…”

Exploration of Horizontal Information Transmission through Social Learning in Juvenile Atlantic Spotted Dolphins (Stenella frontalis)

“…The community includes approximately 100 individuals on any given year, although up to 330 have been identified over the decades (Elliser & Herzing, 2014). Age class coloration is modified relative to that described for pantropical spotted dolphin Stenella attenuata (Perrin, 1970), with four consecutive developmental color classes identified for increasing levels of age-related skin pigmentation: two-tone, speckled, mottled and fused (Herzing, 1997).…”

“…In a Bahamian community of free-ranging Atlantic spotted dolphins, Stenella frontalis, sexually mature females have a calf every three and a half years on average with a subsequent juvenile period of approximately three years (Elliser & Herzing, 2014;Herzing, 1997). During the juvenile period, the mother teaches the calf how to fish, and, by the time weaning occurs, the calf has become an independent forager partly as a result of vertical transmission (Bender, Herzing, & Bjorklund, 2009).…”

“…Horizontal transmission could facilitate the continuing development of foraging behavior in young dolphins by allowing young dolphins to develop their potential from interaction with more competent models, resulting in a steady state of behavioral development where young juveniles have reached the foraging competency required for survival (Kuczaj, Paulos, Ramos, 2005). The structure of a marine mammal society is complex and responds to a variety of factors, including human activity (Ansmann, Parra, Chilvers, & Lanyon, 2012;Chilvers & Corkeron, 2001;Chilvers, Corkeron, & Puotinen, 2003;Elliser & Herzing, 2014;Mann & Watsoncapps, 2005). Understanding social-cognitive processes occurring within the social structure is important from a cognitive, welfare, educational, and evolutionary perspective (Mendl & Paul, 2004).…”