Whales in mourning study

Whales and dolphins carry their dead offspring aloft, often flanked by other adults, marine biologists have found.

A paper (Reggente et al, 2016) in the Journal of Mammology studied seven whale species carrying dead calves and juveniles. Fourteen incidents from three oceans have provided the first records for grieving behaviour in these whale species, from the huge sperm whale to the little spinner dolphin.

Mammals in the study included:

• Indo-Pacific bottlenose dolphins(Tursiops aduncus)
• spinner dolphins (Stenella longirostris)
• killer whales (Orcinus orca)
• Australian humpback dolphins(Sousa sahulensis)
• sperm whales (Physeter macrocephalus)
• Risso‘s dolphins (Grampus griseus)
• short-finned pilot whales(Globicephala macrorhynchus)

Barbara King, emeritus professor of anthropology at the College of William and Mary in Virginia, United States and author of How Animals Grieve, defines animal grief as “emotional distress coupled with a disruption of usual behaviour”.

Study co-author, Melissa Reggente – a biologist at the University of Milano-Bicocca in Milan, Italy – argued about the whales, saying: “They are mourning. They are in pain and stressed. They know something is wrong.”

The study also found reports of mother whales supporting dead calves in their mouths, pushing them through the water and touching them with their fins. Sometimes the offspring were in an advanced state of decay, suggesting they had been carried for some time.

Grieving behaviour

In one incident, short-finned pilot whales in the north Atlantic Ocean formed a circle around an adult and dead calf. In another, a spinner dolphin in the Red Sea pushed a young animal’s body towards a boat. When the boat’s occupants lifted the carcase on board, the entire group of nearby dolphins circled the boat before swimming away.

Ms King agreed such incidents suggested the marine mammals were grieving the dead. She also acknowledged the mammals couldbe displaying curiosity, exploration or nurturing behaviour.

But “it‘s undeniable we can also read something of the animals’ grief in the energy they expend to carry or otherwise keep dead infants afloat, to touch the body repeatedly, to swim in a social phalanx surrounding the primary affected individual”.

Such behaviour is, of course, of no benefit to the mourner – a whale watching its dead is also denying itself food and social support.

Scientists on a boat in the Red Sea observed an Indo-Pacific bottlenose dolphin pushing the badly decayed corpse of a smaller dolphin through the water.

After researchers roped the dead animal and began towing it to land, the adult swam alongside, sometimes touching the body, until reaching water that was dangerously shallow. Long after the scientists had disposed of the body, the adult remained just offshore. The relationship of the two dolphins was not known, but it is likely they were mother and child or closely related, Reggente said.

At times, researchers have firmer cues about the relationship between the mourner and the dead. A female killer whale known as L72 was spotted off San Juan Island in Washington, United States, bearing a dead newborn in her mouth. L72 showed signs of having recently given birth.

“She was trying to keep the [dead] calf up at the surface the entire time, balancing it on top of her head,” said study co-author Robin Baird of Cascadia Research Collective in Olympia, Washington, United States.

A killer whale mother and her offspring often spend their whole lives together. When one dies, Baird argued “the animals go through a period where they’re experiencing the same kind of emotions you or I would when a loved one dies”.

Prevalence among species

Scientists have found a growing number of animals – from giraffes to chimps to crows – behave as if stricken with grief. Elephants are well known for returning again and again to the body of a dead herd member. Dairy cattle vocalise extensively for days after their calves are taken away. Such findings fuel the debate about whether animals experience emotion – and, if they do, how such emotions should influence human treatment of other creatures.

The researchers concluded: “The present study helps to corroborate that adults mourning their dead young is a common and globally widespread behaviour in long-lived and highly sociable/cohesive species of mammals.”