Shy Or Bold? Dolphin Personalities Determine Social Roles And Potential Threats

Social animals interact and form relationships to make sure that their social groups stay together and behave harmoniously towards each other, aiding group survival and fitness. There is a lot of ongoing research aimed at understanding the mechanisms behind social structures. How relationships between animals develop regulates the transmission of genes, pathogens, and information. Meanwhile, scientific research uncovers individual variation in personality or behavioral syndromes in more and more species. 

In this study, researchers set off to see whether this is also true for bottlenose dolphins, and whether their personalities affect how they respond to novel stimuli and form social groups. Dolphins who live off the Northeastern coast of Sardinia, an Italian island, were observed between 2004 and 2013. The researcher employed the shy-bold continuum, a system often used to associate personality with responses to novel, risky, or challenging situations. Here, ‘shy’ individuals are seen as those who are less likely to approach a novel object or to investigate a potential predator. This trait also defines how animals relate to one another. Shy wild songbirds, for instance, were previously shown to form stronger and more stable relationships than bold individuals. Shy captive fish, on the other hand, prefer to associate strongly with fewer individuals. Homophily, where bold individuals prefer being around other bold individuals and vice versa, was also observed in wild fish and captive mammals.

The study found that there was enough suitable data to identify 24 individuals and monitor their behaviors. Calves (young dolphins) were excluded from all analyses as there was evidence suggesting that their choices and behaviors could be influenced by their mothers. Experiments were designed so that it would be possible to measure the reaction of individual dolphins towards two novel and potentially threatening situations: an acoustic harassment device and the presence of a diver with snorkeling gear.

There were no differences between the sexes in terms of their personalities and no significant association with age. Meanwhile, evidence showed that shy individuals had stayed on the outskirts, while the bolder dolphins had enjoyed more central roles within the groups. This suggests that bold individuals may play a critical role in group cohesion, stability, and the sharing of information. Contrary to the findings in fishes, bottlenose dolphins were not seen preferring to be with similar personality individuals. However, the researcher highlights that the small sample size might not allow for evaluating this definitively. Interestingly, one’s exploratory activity and the degree of interaction with an off-shore fish farm were not dependent on the particular dolphin’s personality. 

The potential implications of these results include the fact that due to their boldness, some dolphins may be less concerned about or not perceive the potential threats posed by novel stimuli adequately. This could lead to a higher risk of injury or death due to interaction with human activities. On the other hand, acoustic harassment devices are hypothesized to have a greater impact on shy individuals due to higher stress levels experienced by such animals.

This study provides additional evidence for the existence of social personalities in nonhuman animals and contributes to our understanding of what role personality plays in how mammals associate with one another. The study also highlights that we should advocate for fish farm management practices that are safe for both shy and bold aquatic animals.