Friends Again: Bottlenose Dolphins Unite
Two groups of bottlenose dolphins, once living apart in a bay in Australia, have joined together and become one.
The dolphins of Moreton Bay, near the city of Brisbane, Queensland, had previously lived as completely separate groups. One group foraged on the bycatch (waste) thrown overboard by fishing trawler boats. The other group hunted their own fish. They never interacted or shared food with each other.
This rift was very unusual. When it was first discovered over 20 years ago, it was the only recorded example of a single animal population living as distinct social groups. The phenomenon was dubbed, “the parting of the pods.”
Recently, large areas of Moreton Bay have become protected, banning trawler fishing and reducing fishing in the Bay by 50%. This event has allowed scientists—who had been studying the dolphin population since the 1990s—to see the impact of the change on the dolphin society.
The scientists observed something remarkable. The dolphins of Moreton Bay completely restructured their community, uniting as a single population. Researchers could tell the dolphins apart by nicks and notches in their dorsal fins, and so could see clearly that the groups had come together.
It seems the trawler dolphins decided that with most of their food gone, it would be much better if they worked with the fisher dolphins to find food. There may have even been a “peace broker” who convinced the two groups to join. Scientists believe the joining of the pods is further evidence of dolphins’ amazing intelligence.
Intelligence and alliances
Dolphins are known to be extremely smart. Their brains are as complicated as humans—maybe even more so. They have complex communication skills, using clicks and whistles as their secret language.
Bottlenose dolphins have very strong societies, living permanently in pods. Groups close to shore number between 5 and 20 members. Off shore, pods can be much larger, going into the hundreds. Their bonds are very close, and they constantly interact physically with each other, touching, chasing and talking together. As close as pods are, dolphin societies can also be very versatile, forming alliances with others in times of need. Dolphins often work together to fight against predators, attract mates, and find food.
Scientists think the latter reason is behind the Moreton Bay dolphins’ reunion. Dr. Ina Ansmann, of the University of Queensland, is the lead author of a recent article about the restructuring of the dolphin society. She said, "When relying on natural food sources I guess it's more important for them to interact with others, or to learn from others, or to co-operate with others to get to these food sources.”
It’s certain that these friendly dolphins will continue to teach the researchers about their ways, as they adapt and socialize in the clear waters of Moreton Bay.