First Report of a Common Dolphin (Delphinus delphis) Feeding Alongside Indo‐Pacific Humpback Dolphins (Sousa chinensis) in the Beibuwan Gulf, China

Abstract

ABSTRACT Research on mixed‐species groups of cetaceans has increased worldwide in recent decades; however, their drivers are not well understood. Although the common dolphin (Delphinus delphis) and Indo‐Pacific humpback dolphin (Sousa chinensis) do not form a sympatric community and exhibit different patterns of diet and activity, we observed, for the first time, a mixed‐species group in the Shatian waters of the Beibuwan Gulf, China (a typical habitat for the latter species) on the 3rd and 6th of May 2022. On both occasions, two humpback dolphins were closely accompanied by a common dolphin identified by its distinctive body features. During an approximately 6‐h period of observation, the mixed group exhibited a concentrated use of a very small area in shallow waters and proximity to the coast. Behavior analysis showed that foraging was the most frequently observed activity, followed by socializing, traveling, and resting, which may provide confirmation of the foraging advantage hypothesis for the mixed species group. Our findings are the first to show that the common dolphin and Indo‐Pacific humpback dolphin are mixed‐species groups that expand the known mixed groups of cetaceans.

Keywords

• Beibuwan gulf
• common dolphin
• feeding
• Indo‐Pacific humpback dolphin
• mixed group