In August 2021, a female orca (Orcinus orca) named Sædís was seen swimming with a pilot whale (Globicephala melas) calf in western Iceland. Experts said it is the first documented of such interspecies adoption, Insider reported.
Investigators discovered that Sædís was not only swimming with the young whale but is also actively caring for it. They saw two more orcas that likely came from Sædís' pod, although there were no other pilot whales seen near them, which is uncommon since they are known to travel in pods.
Pilot whales
Interspecies Adoption: Orca Adopts a Pilot Whale Calf
When researchers on a whale-watching boat in Iceland saw the female orca swimming alongside an odd youngster, they noticed that the little animal lacked the white mark near its eye that orcas have and, as it turned out, was not even of the same species.
Marie-Thérèse Mrusczok, an orca researcher, was working as a spotter on the boat's top deck when she sighted the orca and what she suspected was a pilot whale at the west of the island.
She told Live Science that she was unsure of what she saw at first but when she came down from the top deck to check, the whole crew was also amazed at finding what they initially thought was the tiniest orca calf they have ever seen.
Mrusczok told the team that it was not an orca calf. She then contacted experts who verified that what they had seen was a long-finned pilot whale calf.
Mrusczok and her colleagues published their results in the Canadian Journal of Zoology on February 17th under the title "First account of apparent alloparental care of a long-finned pilot whale calf (Globicephala melas) by a female killer whale (Orcinus orca)", in what might be the first documented occurrence of an orca caring for the babies of another species.
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Possible Explanations for Why the Orca Adopted the Pilot Whale
Before the boat went away, the researchers observed the orca and calf for 21 minutes. At the time, the orca appeared to be looking for the pilot whale. Mrusczok explained that the female orca was displaying protective and caring behavior for the pilot whale calf.
However, as Live Science reported, it is evident that the calf is in poor condition and that it is unlikely that Sædís was feeding it. In the nine years researchers have been studying Sædís, she had not had any calves perhaps due to her old age, and was not producing milk. When she was spotted in 2022, the calf was not yet with her.
Mrusczok said that the calf most likely died, although it is still a mystery how the two came together. One explanation offered in the study was that the orca came across the pilot whale calf and adopted it as its calf.
Another reason could be that the orca abducted the calf. Pilot whales in Icelandic waters are known to chase orcas possibly due to food competition or perceived predation risk.
Mrusczok and her team are collecting data every year on the social interactions between the two species to hopefully learn more about interspecies adoption.
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