Dear colleagues, My co-authors and I are pleased to share our new publication "The partial merger of two dolphin societies" published in Royal Society Open Science. A PDF is freely available using the link below. Danaher-Garcia N, Connor R, Fay G, Melillo Sweeting K, Dudzinski K (2022) The partial merger of two dolphin societies. *R Open Sci.* 9:211963. https://doi.org/10.1098/rsos.211963 ABSTRACT: Interactions between mammalian social groups are generally antagonistic as individuals in groups cooperate to defend resources from non-members. Members of the familyDelphinidae inhabit a three-dimensional habitat where resource defence is usually impractical. Here, we describe a long-term partial fusion of two communities of Atlantic spotted dolphins (Stenella frontalis). The northern community, studied for 30 years, immigrated 160 km to the range of the southern community, observed for 20 years. Both communities featuredfission–fusion grouping patterns, strongest associations between adult males, and frequent affiliative contact between individuals. For the 5-year period following the immigration,we found members of all age classes and both sexes in mixed groups, but there was a strong bias toward finding immigrant males in mixed groups. Some association levels between males,and males and females, from different communities were as high as the highest within-community associations. Affiliative Contacts indicate that these individuals were forming social relationships.The mixing of two separate social groups with new bond formation is rare in terrestrial mammal groups. Such Mixing between spotted dolphin groups suggests that adaptations to respond aggressively to outsiders are diminished in this species and possibly other ecologically similar dolphins. Please, do not hesitate to contact me at nicole@dcpmail.org. I would be happy to answer any questions about the study. Best regards, Nicole -- Nicole A. Danaher-Garcia, Ph.D. Postdoctoral Associate Florida International University | Dolphin Communication Project ndanaher@fiu.edu | nicole@dcpmail.org