The science behind why dolphins in Australia are delivering "gifts"

Delivery service is having a moment for humans and also, apparently, for dolphins in Australia.

In Australia's Tin Can Bay, the local humpback dolphin population is used to human tourists being around — specifically, tourists who pay to feed them fish.

But the Covid-19 pandemic has meant that fewer humans are around to shower the dolphins with tasty treats. In recent weeks, these dolphins developed a unique response to empty shores: they're bringing "gifts" to the places people usually visit.

These gifts come in the form of bottles, chains, bits of coral, and barnacle-covered rocks from the bottom of the ocean. Several individuals in the local pod are bringing gifts, including 29-year-old Mystique the dolphin. He was known for bringing humans gifts even before the pandemic.

The photos of dolphins bringing marine memorabilia were first shared on Facebook by Barnacles Cafe, a spot that sells fish to tourists to feed the dolphins ($5 for entry and another $5 for the feeding experience).

Barnacles had been closed down in light of the pandemic — although the cafe decided this week to reopen on weekends — and volunteers noticed that the local dolphin pod was responding to the shutdown.

"The pod has been bringing us regular gifts, showing us how much they’re missing the public interaction and attention," the cafe wrote on Facebook. "They are definitely missing you all."

The idea that dolphins are missing humans is a lovely sentiment, but it's important to note that they're more likely just missing free fish, Barry McGovern, a Ph.D. student studying dolphin behavior at the University of Queensland, told 7News.

"In all likelihood, they probably don’t miss humans per se," McGovern said. "They probably miss a free meal and the routine."

That underscores something researchers already knew about dolphins: Bringing gifts to get what they want is classic dolphin.

Giving gifts for personal gain — Dolphins like to carry all kinds of things — branches, shells; sea cucumbers. But there's evidence that gift-giving has a specific role in dolphin behavior, including attracting the attention of a mate.

Previous research suggests that male dolphins tend to bring one particular present to females: sea sponges. These are commonly exchanged between adult male suitors and their potential lady friends.

Male dolphins sometimes deliver the sponge with a little flare, posing with their tail above the water (called a “banana pose”) or give a little trumpeting sound from their blowholes. It's kind of a big moment.

But we can't say for sure that dolphins bringing sea sponges to typically human-dominated areas means they're extra thirsty for humans' attention — or even their food. In fact, the Tin Can Bay dolphins might just be bored and messing around, McGovern said.

Dolphins "often play with bits of weed and coral and all sorts of things," he said. “They’re used to getting fed now, so they’re used to humans coming in. When it’s not happening, maybe it’s just out of boredom.”

Given the tactics that humans have come up with to stave off boredom during social distancing — see: gerbil art museum — dredging up coral pieces really isn't that hard to believe. That's said, it's not great that these dolphins even know to come to Tin Can Bay: In the United States, it's illegal to feed a dolphin because when they're fed, "they learn to beg for a living."