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Complex social structure, alliance stability and mating access in a bottlenose dolphin 'super-alliance'
R C Connor1, M R Heithaus, L M Barre
1Department of Biology, University of Massachusetts at Dartmouth, 02747, USA. rconnor@umassd.edu
Proceedings. Biological Sciences
|February 24, 2001
Summary
Male bottlenose dolphins (Tursiops aduncus) form large alliances, but contrary to the equivalence model, their relationships are complex. Alliance stability and partner preferences reveal a sophisticated social structure within the Shark Bay super-alliance.
Area of Science:
- Behavioral Ecology
- Animal Social Networks
- Marine Mammal Cognition
Background:
- Large brain size in mammals correlates with complex social relationships and alliances.
- Indian Ocean bottlenose dolphins (Tursiops aduncus) in Shark Bay exhibit one of the largest known male social networks outside of humans.
- These male alliances cooperate to gain access to receptive females.
Purpose of the Study:
- To test the 'equivalence rule' hypothesis regarding the simplicity of social relationships within a large dolphin male alliance.
- To investigate the internal structure and dynamics of the Shark Bay bottlenose dolphin super-alliance.
- To determine if alliance stability and partner preferences are uniform or differentiated among males.
Main Methods:
- Analysis of 100 consortships within the Shark Bay bottlenose dolphin super-alliance.
- Statistical examination of alliance stability and partner preferences among 14 males.
- Correlation analysis between alliance stability and consortship rates.
Main Results:
- Data from 100 consortships contradict the equivalence hypothesis.
- The 14 males within the super-alliance displayed significant differences in alliance stability.
- Partner preferences varied notably among males, indicating a complex internal social structure.
- Alliance stability was positively correlated with consortship rate, suggesting competition influences relationship differentiation.
Conclusions:
- The social structure within the bottlenose dolphin super-alliance is more complex than predicted by the equivalence rule.
- Differentiated relationships and partner preferences suggest a sophisticated social hierarchy and competition for female access.
- Male dolphin alliances are not based on simple equivalence but on complex, competitive social dynamics.
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