In what has been described as a first-ever account of such an event taking place, scientists were able to observe an adult male orca and his mother killing a newborn calf.
Although the incident took place in December 2016, it was only last week when a trio of researchers published their account of what happened in the journal Scientific Reports. According to the researchers, the attack marks the first time infanticide has been observed in killer whales, and, as Live Science noted, the only known case of a male orca and his mother jointly committing the act.
Speaking to the Washington Post, Fisheries and Oceans Canada cetacean researcher Jared Towers explained that he and his colleagues didn’t expect anything unusual when they were photographing a pod of killer whales off the coast of Vancouver Island. That changed when they witnessed a series of “erratic movements,” and while it was assumed that the orcas were attacking their usual prey, the scientists soon realized that a killer whale calf they had photographed earlier in the day didn’t surface.
“The baby was hanging out of his mouth,” Towers recalled.
“I knew right off the bat — I study killer whales pretty intensively — that this was a ‘first of its kind’ observation.”
In a detailed explanation of how the adult male orca ultimately killed the newborn calf, Live Science wrote that Towers and his fellow scientists saw three killer whales aged 2- to 13-years-old being chased by a 32-year-old male orca and his 46-year-old mother. The three younger whales were able to swim toward their other family members, which included their other siblings and their 28-year-old mother. This group of siblings included the aforementioned newborn, or neonate.
While the baby whale and its family tried their best to head to safety by swimming westward, the researchers wrote in the new paper that their two predators eventually caught up with the large group, with the newborn calf hanging out of the 32-year-old male’s mouth, as Towers had described to the Washington Post.
In the five hours that followed, the researchers observed the adult male orca killing the calf by drowning it, with the baby’s mother unable to do anything to stop the attack. The male attacker’s mother reportedly helped out in the killing, throwing herself in front of the baby’s mother and further preventing her from saving her newborn.
“We were a bit horrified, but more so I think we were fascinated,” Towers told the Washington Post.
“We knew that it was time to just collect as much data as we could to accurately record our observations.”
It isn’t sure why animal infanticide, regardless of species, takes place, but Live Science wrote that such acts might be sexually driven, based on previous research that had posited males kill the children of their potential mates to prevent them from lactating. As for the recently documented killer whale infanticide case, Towers said that there’s still no proof to suggest that the adult male orca and the mother of his newborn victim had mated after the attack. This might change, however, if the mother gives birth to a new calf in the coming months, as the orca gestation period usually takes 17 to 18 months.
As for the reason behind the male orca’s mother helping him kill the newborn calf, the researchers hypothesized that females of the species who have passed reproductive age tend to travel alongside their sons, and help them as they hunt for prey. Interestingly, the study also suggested that mother orcas get involved as their adult sons look for potential mates, in hopes of preserving their lineage.