What is a dolphin 'group'?

That group-living animals mainly exist in groups is pretty straightforward. What is less straightforward is how to define what constitutes a group, particularly for elusive and socially intelligent creatures like bottlenose dolphins.

In areas of high dolphin densities - like the Amvrakikos Gulf - it is common to see plenty of dolphins spread around the boat at various distances. Should all of these individuals be categorised as a single group, even though it is virtually impossible to count those further away? Or should you set a radial boundary with your boat as a reference point and only regard those individuals that move within that circle as a group? Or maybe solely count those animals engaged in the same behaviour? And surely, shouldn’t there be a standardised methodology of how to define a group across research sites? These are some of the questions I am trying to clarify and answer in the context of my Master thesis here in the Amvrakikos Gulf.

Each day that Joan, the volunteers and I venture out in the Gulf I count the dolphins according to different group definitions. The immediate aim is to analyse the discrepancy in group size estimates that they might yield, as well as determine which definition is most appropriate for the Amvrakikos Gulf. The overarching objective is also to bring attention to the conservation and ecological (etc.) importance of using a standardised group size definition, and come up with a suggestion of what such a methodology might entail.

Theoretically it might seem like an easy job, but the field is a different empirical matter. After two weeks of field work, my experience is this - in nature, things are often more intricate and complex than what they appear at first glance, and on philosophical days I’m inclined to agree with Socrates ‘all I know is that I know nothing‘. But, to me that’s also the charm about research - it’s challenging and requires complete immersion of all your faculties. And of course, the curiosity involved in not being able to predict where an experiment might take you.

Christina Geijer