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Group size, partner choice and collaborative actions in male Indo-Pacific bottlenose dolphins (Tursiops aduncus)


Due to the diversity of the phenomenon, dolphin cooperation has attracted considerable research interest in both wild populations and those under human care. Dolphins cooperate in various contexts, including group hunting, alloparental care, social learning, social play and alliance formation for securing mates. This investigation focused on the effect of group size and partner choice in a cooperative task using systematic group testing. A cooperative enrichment device was made of a PVC tube containing fish and ice that was temporarily sealed with two PVC caps with rope handles attached. The device was designed to be operated by pairs of dolphins, opened by simultaneous pull of its two handles. The analysis focused on two behaviours, cooperative opening and cooperative play with the device. Testing focused on an adult male dolphin group including four to six individuals and using a single or two devices. Altogether five group testing arrangements and a pairwise testing phase were conducted. Out of the six dolphins, five showed active involvement. All ten possible pairs of the five active dolphins were successful in opening and playing with the device cooperatively. Cooperation increased with group size, but the social networks showed no significant differences among group arrangements. However, the cooperative pairs showed a significant difference in success rate during pairwise vs group testing, while demonstrating a strong partner preference. This study provides the first evidence for partner choice with regards to cooperation in male dolphins.

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We thank the Marine Mammal Department of Ocean Park Hong Kong for their support during our experiment. We would also like to thank Xiao Lin for his valuable comments regarding the data analysis. Special thanks to S. A. Kuczaj, who provided invaluable help on planning the experiment and for his inspiration and encouragement.


This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. ÁP was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences and the ÚNKP-20-5 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research, Development and Innovation Fund.

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Correspondence to Eszter Matrai.

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The project was approved by the Animal Welfare, Ethics and Care Committee of Ocean Park Conservation. Ocean Park gained accreditation from the Association of Zoos and Aquariums (AZA), it is also a member of the World Association of Zoos and Aquariums (WAZA). The animal welfare standards at the Park were also approved by the American Humane Association under its Humane Conservation™.

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Matrai, E., Kwok, S.T., Boos, M. et al. Group size, partner choice and collaborative actions in male Indo-Pacific bottlenose dolphins (Tursiops aduncus). Anim Cogn 25, 179–193 (2022).

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  • Male–male collaboration
  • Cognitive enrichment
  • Alliance formation
  • Partner preference
  • Cooperative problem-solving