These dolphins display a remarkable range of abilities. They solve intricate problems, alter their surroundings to their advantage, and coordinate sophisticated hunting strategies. They can pass on knowledge and skills to peers, recognize themselves in a mirror, and communicate through a complex system that researchers believe is highly developed. They stand out as extraordinary animals, likely among the most intelligent on Earth after humans. A global team of researchers has shown that they form vast, multi-level alliance networks—the largest known among non-human species. These cooperative ties help access contested resources.
Male bottlenose dolphins (Tursiops truncatus) form pairs and trios to search through coordinated consortia of individual females that they monitor closely. Some of these male groups remain remarkably stable for decades, earning the label first-order alliances by scientists.
These male doubles and triples are then integrated into larger units. Between four and fourteen individuals form secondary alliances. These teams have persisted for decades and compete with other alliances for access to females, often shifting alliances or defending their own.
Even larger groups exist, described as third-class alliances, typically forged when conflicts arise among weaker groups. Dozens or even hundreds of dolphins participate, with members of subordinate alliances cooperating across boundaries.
A team led by researchers from the University of Bristol, with collaborators from the University of Zurich and Massachusetts, examined the alliance structure among 121 adult male Indo-Pacific bottlenose dolphins in Shark Bay, Western Australia. The findings appeared in the Proceedings of the National Academy of Sciences (PNAS).
strategic relations
Collaboration among allies is common in human societies and is central to our species’ success. Strategic relationships at multiple social levels resemble commercial or military alliances, yet they were once thought unique to people. That view is being reexamined, according to the study’s lead author, Stephanie King.
Not only do male bottlenose dolphins form the largest known multi-level alliance network outside humans, but the cooperative links between groups — not just alliance size — raise reproductive success by allowing more time with females, notes a Bristol School of Biological Sciences associate professor.
Researchers also found that these teams mate with females when tertiary allies are on good terms. Social bonds between alliances contribute long-term benefits for the males, explains Simon Allen, Senior Lecturer in the same department, who contributed to the study.
Until recently, intergroup cooperation was thought to be unique to humans and tied to pair bonds and kinship maintained by males. This research suggests otherwise.
Cross-group alliances can arise without those features, indicating a social and mating system more akin to that observed in chimpanzees, a conclusion drawn by Richard Connor, professor emeritus at the University of Massachusetts and now affiliated with Florida International University, who co-directed the study with King.
very strong social ties
The 2022 publication of the importance of third-level or intergroup alliances in dolphins resonates with Shark Bay’s long-running research and marks the 40th anniversary of that work and the 30th anniversary of its 1992 publication on male alliance formation.
In the words of Michael Krützen, who leads the Zurich Anthropology Institute, this work shows that important insights into the evolution of traits once thought to be uniquely human can be gained by studying highly social, intelligent taxa beyond primates.
Two bottlenose dolphins performing a playful pirouette underscore the sensory richness of these animals.
The study highlights that dolphin societies and non-human primates offer valuable models for understanding the evolution of human social and cognitive traits. This idea echoes the earlier findings that bottlenose dolphins cooperate in pairs and trios and are part of larger alliance networks. The strong social and emotional bonds within dolphin communities create complex, open social networks where members support each other in times of trouble.
Dolphins are celebrated for their intelligence, including the ability to plan nutrition strategies for various environments. For example, Patagonian dolphins herd flocks of anchovies into globes and then feed on them. In Florida Bay, bottlenose dolphins devised a strategy to catch mullet by lifting mud curtains from the seafloor to trap fish as they jumped over the rings.
extraordinary ability to solve problems
Relative to body size, the bottlenose dolphin possesses one of the largest brains among animals, which may explain their capacity to tackle complex problems. In the Florida Keys, researchers observed two dolphins realizing in seconds that the only way to remove a cap from a PVC pipe filled with fish was to cooperate, and they did so by working together.
Some scientists contend that every dolphin may invent a unique whistle name while still a calf and continue using it for life, forming acoustic signatures. Dolphins are notably vocal and use their sonar to perceive objects with remarkable precision, distinguishing metal, plastic, and wood at considerable distances.
The dolphin social networks are extremely intricate, demonstrating high cohesion and solidarity. When one or more individuals encounter trouble, the group often comes to help, and mass strandings can occur when groups converge around a single individual in distress.
Cited research: PNAS article by King, Connor, and colleagues on alliance structure in Shark Bay dolphins.