Male Alliances

Since 1987 Dr. Richard Connor has focused his research on male alliances. In Shark Bay, alliances of 2-3 males cooperate to herd individual females for periods of up to over a month. Some alliance partners are nearly always found together and their bonds may last for years.

Richard and his colleagues have been following one such pair of males, Real Notch and Hii, for fifteen years (Hii is pictured with close associate Bottomhook on right). They think that by cooperating in an alliance, the males can prevent their female consort from mating with other males and other males from mating with her.

Unfortunately for the males, females appear to have countered this male strategy with one of their own: they come into estrus several times the year they conceive making it very hard for any group of males to insure that one of their members fathers her offspring.

Incredibly, they found that teams of alliances cooperate to attack other alliances to take their females. Thus, there are two levels of male alliances in our dolphin society, the alliances that herd females and teams of alliances that steal them.

This was a very exciting discovery!, because such nested levels of male alliances are common in human society but very rare even in non-human primates. The key is that both levels of alliance occur within a single dolphin society, not between two different societies.

Many birds and mammals form groups to defend their turf, but these are all ‘us against them’ interactions–nothing complicated about that. But in social groups, dolphin alliances can take on the dimensions of a soap opera, with individuals using friendly behavior to compete for favored allies in a strategic fashion to enhance their social position. Such alliances within groups are common in primates but rare elsewhere-and dolphin males have two levels of such alliances!

But the story does not end there. In the 1990s they documented a ‘super-alliance’ of 14 males that, not surprisingly, handily defeats other alliances in their area. Members of the super-alliance still get together in groups of 3 for the purpose of herding a female, but to their surprise, they found that after a trio of males finished herding one female, the males often joined a different trio to herd another one (but only with other members of the super-alliance). This came as quite a surprise after years of watching the stable alliances that always stuck together.

Richard and his colleagues suspect that the males have to cooperate with a larger number of super-alliance members to maintain a degree of cohesion in the group. His future research will focus on finding other large alliances to see if alliance stability correlates with group size and on discovering the ecological and genetic bases for alliance formation.