Dear all, My co-authors and I are pleased to announce the publication of our review on the definitions of delphinid groups in the journal Ecology and Evolution. Syme, J., Kiszka, J. J., & Parra, G. J. (2022). How to define a dolphin "group"? Need for consistency and justification based on objective criteria. Ecology and Evolution, 12(11), 1-18. https://doi.org/10.1002/ece3.9513 Abstract: Group living is a critical component of the ecology of social animals such as delphinids. In many studies on these animals, groups represent sampling units that form the basis of the collection and analysis of data on their abundance, behavior, and social structure. Nevertheless, defining what constitutes a group has proven problematic. There is inconsistency in the terms and criteria used and many definitions lack biological justification. We conducted a literature review and an online expert survey to assess various terms (group, school, party, and pod), and their definitions as applied to delphinids to identify issues to ultimately make recommendations. Of 707 studies analyzed, 325 explicitly defined one or more terms, providing 344 definitions. Additionally, 192 definitions were obtained from the survey. Among these definitions, group was the most common term used (review: 286 definitions, 83.1%; survey: 69 definitions, 35.9%) and the most familiar to the survey respondents (73 respondents, 100.0%). In definitions of group, spatial proximity was the most used criterion (review: 200 definitions, 71.2%; survey: 53 definitions, 81.5%) followed by behavior (review: 176 definitions, 62.6%; survey: 38 definitions, 58.5%). The terms and criteria used to define delphinid groups vary considerably. Rather than proposing a single formal definition, we instead recommend that the term group and spatial proximity criteria be used to define sampling units of individuals observed in the field. Furthermore, we propose a process for formulating definitions that involves analyzing interindividual distances to determine naturally occurring patterns that are indicative of group membership. Although this process is based principally on the spatial proximity of individuals, it could also incorporate the behavior of group members by evaluating the influence of behavior on interindividual distances. Such a process produces definitions that are biologically meaningful and compatible across studies and populations, thus increasing our ability to draw strong conclusions about group living in delphinids. You can find the full article here: https://onlinelibrary.wiley.com/doi/10.1002/ece3.9513 Thank you to all who took the time to complete the online survey. Please feel free to contact me with any questions at jonathan.syme@flinders.edu.au<mailto:jonathan.syme@flinders.edu.au> Kind regards, Jonathan Syme PhD Candidate CEBEL, Flinders University