More Gay Dolphins Observed Off Coast of Western Australia

bottlenose dolphin
Bottlenose dolphin. Mike Blake/Reuters

Homosexual behavior in the animal kingdom is rife. One of the best-known examples is among bottlenose dolphins, with both males and females having encounters with members of the same sex.

The exact reasons for the behavior are not well understood, but social bonding is thought to be a factor.

Researchers in Australia are looking to solve the mystery. They recently observed big groups of dolphins engaging in what appeared to be homosexual behavior. A team from the Mandurah Dolphin Research Project in Western Australia noticed the males started spending quality time together after their mating season was over.

"These dolphins, all but three of them juveniles, organized themselves in four subgroups in which they were observed engaging in socio-sexual behavior that included mounting and genital contact between individuals," Krista Nicholson, of Murdoch University, told the Mandurah Mail.

"The subgroups joined, frequently forming a large group, and then split again in different group compositions."

This is typical behavior seen in other bottlenose dolphin populations, Nicholson said, including those found in Shark Bay. Scientists have studied this group extensively, with researchers examining bisexual behavior and the population's social setup.

"Apart from homosexual behavior, males, unlike females, in Shark Bay have also been recorded to perform synchronous displays," she said. "In Shark Bay, where male dolphins form lifelong alliances, socio-sexual interactions between males are more common than between females or between the sexes."

Finding another relatively nearby group of dolphins engaging in similar behavior will help researchers better understand how and why it happens.

Nicholson added that homosexual behavior appears to play a role in the development of social bonds between males, helping them to establish dominance and alliances.

Janet Mann, who has studied dolphins at Shark Bay for decades, says another possible reason is for males to practice mating. In the book Homosexual Behaviour in Animals: An Evolutionary Perspective, she wrote: "Homosexual interactions in bottlenose dolphins...seem to serve multiple functions, although the exact fitness consequences, if any, are unknown.

"Our understanding of the social structure and relationships in a larger context would suggest that male-male social-sexual interactions are significant for the development of close bonds or alliance formation, negotiating dominance relations within and between eventual alliances, and practicing courtship behaviours for adulthood."