A video of a female humpback whale and its stillborn calf, taken near the Gold Coast, is a rare glimpse into the species' reaction to death, researchers say.
The footage, filmed in waters off Palm Beach in July last year, shows a whale interacting with its deceased calf immediately after giving birth.
The mother approaches the calf several times, touching it with its head and fin, then lies still alongside the newborn's body.
The female and another "escort" whale remained with the stillborn for at least two hours.
Members of the public spotted two adult humpbacks in the same area over the next two days, although it was not confirmed if they were the same animals.
Dr Olaf Meynecke, a marine scientist at Griffith University's Whales and Climate Research Program, said the "post-mortem attentive behaviour", sometimes referred to as grieving behaviour, shown towards the calf had not been seen in humpback whales before.
Dr Meynecke co-authored a report of the encounter, published in the Discover Animals journal.
"Having the background knowledge of the strong bond between mother and calf, and then witnessing the response of a female towards a stillborn is obviously a very unique way of observing animal behaviour and understanding what the responses might be when a situation like this occurs," Dr Meynecke said.
"They were not travelling, they were not socialising, and they were staying in the same spot and milling or turning around in the same area.
SeaWorld Foundation rescue boat captain Andrew Mulville was on a day off fishing with his son when he was asked to check on the whales, which had been reported as acting strangely.
After he realised one of the whales had given birth to a stillborn calf, he decided to film the encounter with an underwater camera.
Mr Mulville said after 25 years caring for sick whales, seeing strandings and conducting rescues, he had a good understanding of their typical behaviour.
"That was a huge part of what made me even think to put my head underwater in the first place because it was something I've never seen before," he said.
Grieving behaviour has been more commonly observed among types of toothed whales and dolphins, including instances of Orca whales carrying dead calves for hours or days at a time.
Dr Meynecke said dead humpback calves were much harder to observe, as they are less buoyant and often sink to the bottom of the ocean quickly.
He hopes that more people using drones while in the water will make it easier to document similar events in the future.
"It does help us to understand animals in general much better, also hopefully understand our humpback whales better," Dr Meynecke said.
Macquarie University whale scientist Dr Vanessa Pirotta, who was not involved in the report, said it was "challenging" to interpret the female whale's behaviour.
"For a humpback whale to give birth to a calf and it being stillborn, I would say that there would definitely be at least a reflection on potentially what has happened, given that this mother has been carrying this calf," Dr Pirotta said.
She noted that while humans and whales can share similarities as mammals, it was important not to "anthropomorphise" the behaviour.
"What we can do is we can learn from observations, and that's exactly what science is about," Dr Pirotta said.
