Humpback dolphins (Sousa spp.) are obligate shallow‐water and resident species, and they typically live in fission–fusion societies composed of small‐sized groups with changeable membership. However, we have scant knowledge of their behavioral ecology, starting with potential factors influencing inter‐population variability of their group sizes. Here, we compiled a new global dataset of humpback dolphin group sizes based on 150 published records. Our data indicated an inter‐specific consistency of group‐living strategy among the 4 species in the Sousa genus, as these species preferred living in small‐sized groups with a mean size of mostly no more than 10, a minimum size of single individual or small pairs, and a maximum size of several tens or ≈100. In addition, we clearly showed the geographic variations in group sizes of humpback dolphins at a global scale. We found that the geographic variations in humpback dolphin group sizes were primarily associated with the latitude, sea surface temperature, and abundance. To conclude, our findings provide insights into social dynamics and socioecological trade‐offs of humpback dolphins, and help better understand how these resident animals adapted to their shallow‐water habitats from the perspectives of biogeography and socioecology
We are grateful to the organizations and people that have made contributions to scientific research on humpback dolphins. This study was financially supported by the Major Science and Technology Project in Hainan province (ZDKJ2016009‐1‐1), the National Natural Science Foundation of China (41306169, 41406182, and 41422604), the Ocean Park Conservation Foundation of Hong Kong (AW02‐1920), the Chinese White Dolphin Conservation Action Project of Ministry of Agriculture and Rural of People's Republic of China (Y760091HT1), and the Biodiversity Investigation, Observation and Assessment Program of Ministry of Ecology and Environment of China (2019–2023). The writing of this paper was supported in part by the China‐UK Newton Fund PhD Placement from British Council and China Scholarship Council.
- humpback dolphins
- social dynamics
- geographic variations
- group size