Male Dolphins Attract Females With 'Gifts,' Have Wingmen Help Them Out

Marine biologists from the University of Western Australia (UWA), working off the northwest coast of Australia, have observed a rare mating display in which male dolphins offered large marine sponges to females to attract them for mating.

Dolphins are already known to be very smart with highly complicated social structures and verbal cues to identify each individual. However, this behavior has never been seen before in these highly documented and studied animals.

Scientists from UWA's School of Biological Sciences, the University of Zurich and Murdoch University conducted a decade of boat-based research on coastal dolphins across north-western Australia and published their results in the journal Scientific Reports.

The team was able to successfully document adult male Australian humpback dolphins presenting large marine sponges to females, as well as performing visual and acoustic displays filled with high-pitched yelping and flashy fin work.

A male was seen rushing to the ocean floor to recover a large marine sponge which he placed delicately on the end of his beak to offer it to the female, who was with a calf. Though there have been documented sexual displays in animals, it is still rare in the animal world to woo a member of the opposite sex with gifts. Animal courtship can range from the "normal" to the very "weird." Bonobos court each other, flamingoes form large flocks that perform synchronized moves on water, hippos spray their feces at a female using his tail and hooded seals inflate their nasal septum to form huge red balls of air in front of their face to attract a mate.

Lead author Dr. Simon Allen from UWA's School of Biological Sciences said the findings suggested an as yet unrecognized level of social complexity in humpback dolphins.

"We were at first perplexed to witness these intriguing behavioral displays by male humpback dolphins, but as we undertook successive field trips over the years, the evidence mounted," Allen said in a press release on the University of Western Australia website.

Sometimes, after the male dolphins presented the sponge to the female, he would strike a quick pose for added effect. Some would flex with their tail and stick their tail above water, which the researchers call the "banana pose."

"Here we have some of the most socially complex animals on the planet using sponges, not as a foraging tool, but as a gift, a display of his quality, or perhaps even as a threat in the behavioral contexts of socializing and mating."

Co-author Stephanie King said that the team also observed two or more male dolphins on occasion, some large adult male dolphins also appeared to be working together in pairs. This seems to be similar to the way human men court women in modern times, using wingmen to help them out.

This alliance between two competing males is not usual. They are competitors in search of the same thing. But, these dolphins seem to have figured out that when males help each other — either by mirror posturing or by using their movement to control the movement of female dolphins— male dolphins help each other find mates. The study calls this behavior "cooperative to compete."

"The formation of alliances between adult males for the purposes of coercing females is uncommon since mating success cannot be shared," Dr. King said. "This is a new finding for this species, and presents an exciting avenue for future research," he added.

Next, the researchers hope to determine whether or not presenting sponges and engaging in sexual displays improves an individual's chance of mating success.

The team says that there is a lot to learn about these dolphins. These displays to attract the opposite sex need to be studied further to see if they affect mating success. The team wants to conduct behavioral and genetic studies on these dolphins to study the origin and the use of this courting procedure.