A war is an organized conflict to achieve some goal. Humans fight them all the time. Well Dolphins have their complex relationships too. Some of them turn into fights over, what else, fertile females. Male and female bottlenose dolphins spend their days courting friends and building alliances. Two new studies show just how important such friendships are to dolphins and the role friends and alliances play in life's biggest game: the race to reproduce. Male bottlenose dolphins form tight bonds with friends and allies that are as intricate and devious as those of humans. Males compete for access to females. Such competition can take the form of fighting other males or of herding females to prevent access by other males. Dolphins have been observed engaging females even when they are not in their estrus cycles and cannot produce young, as well as when they can.
In 1992 Shark Bay dolphins were observed as living in a classic fission—fusion society where individuals associate in small groups that change composition frequently. Fission—fusion grouping pattern presents two types of cognitive challenge. First, social relationships occur in a constantly changing social milieu ”˜placing a premium on the evolution of cognitive ability. Second, fission—fusion also introduces uncertainty into an individual's knowledge of third party relations. Changes in relationships between others, even well-known individuals, may occur in other unseen groups or actions. Sound familiar to daily human life?
Researchers already know, for example, that males team up as duos or trios—known as first-level alliances—so that they can mate with a female without her swimming away. (Females come into estrus only every 4 to 5 years and are thus a rare prize.) But rival males will often try to steal the female, causing the duo or trio to join forces with other duos and trios in what is known as a second-level alliance.
"There can be huge battles over a single female," says Richard Connor, an animal behaviorist at the University of Massachusetts, Dartmouth, who has been studying wild dolphins in Shark Bay, Australia, for 24 years. "A trio under attack will get help from their buddies."
Now Connor and colleagues have found an even higher level of alliance. In the biggest fights, the team found, the second-level alliance may receive help from another group of male dolphins, forming what the researchers call a "third-level" alliance. Even among chimpanzees, scientists have not witnessed such sophisticated partnerships, where one group of animals receives help from another group in a fight. The need to keep track of these complex and shifting alliances may help explain why dolphins have such large brains, the researchers reported online in Biology Letters.
The extensive male partnerships are puzzling, says Connor, because receptive females are so rare. "These are rival males, not relatives, and, theoretically, they should avoid each other." They might help allies keep a captured female because at some point in the future, they will be the ones calling for help, he speculates.
Female bottlenose dolphins also have a strong network of female family and friends—and in the second study, Connor and another team of researchers found that this helps them have more calves. The research—reported online in the Proceedings of the National Academy of Sciences—combined genetic analysis with observations collected by Connor's team on 52 female dolphins in Shark Bay. The team found that female dolphins have more calves that survive to age 3 if they have friends (not necessarily relatives) that have also raised calves to that age, when a dolphin calf usually becomes independent.
Again all this sounds so familiar to human type relationships.