A female orca has been giving a newborn long-finned pilot whale an easy ride in the waters off western Iceland, as if the youngster was her own calf. However, the biologists who observed the event are cautious as to whether this is a case of cross-species lifeline for an animal that would have died otherwise, or a whale of a kidnapping. Either way, it’s something never previously described, and provides new insight into the psychology of one of Earth’s most intelligent species.
The fact orcas are also known as killer whales suggests they don’t have the best reputation among humans. Their scientific name Orcinus orca may sound more friendly, but it comes from the same root as orc and ogre - humanity’s dim opinion goes way back. There’s evidence other whales feel the same way, with reports of humpbacks going to great lengths to disrupt orcas from feeding on smaller mammals.
So if pilot whales are looking for a childminding service, orcas probably wouldn’t be top of the list. Consequently, when members of the Orca Guardians Iceland group witnessed an orca named Sædís spending time with a sickly-looking pilot whale calf in 2021, with two other orcas nearby, it justified a report in the Canadian Journal of Zoology.
The calf was not observed nursing, but was swimming in a position that allows it to use less energy, carried along by the adult’s pressure wave. No adult pilot whales were present at the time, so Sædís hadn’t casually become mixed up in a pod and caught a confused young whale in her slipstream. It also appears likely the event ended in tragedy – when the authors re-sighted Sædís the following year there was no sign of the calf, which would have been far too young to survive long-term on its own.
Nevertheless, the report adds to evidence interactions between cetacean species may be more complex than we thought. It follows the astonishing footage in a David Attenborough documentary of dolphins and false killer whales forming super pods to hunt together and greeting each other as old friends.
Although the calf has not been seen again, Sædís was sighted swimming with a pod of long-finned pilot whales the following year, before being repeatedly chased off in a way never reported before. The authors propose this “may represent an active effort to obtain another long-finned pilot whale calf.”
Orcas and pilot whales have been observed closely in recent years off western Iceland, both from whale-watching boats and on land. This has included one case of orcas feeding on pilot whales, but cases of pursuit and predation are more common elsewhere in the North Atlantic. The conflict does not all go one way – groups of pilot whales have been seen chasing orcas, in one case causing them to jump out of the water. The orcas of the area are primarily fish eaters, and it is thought they may represent competition, rather than a predator, to the pilot whales.
Cases where mammals appear to adopt members of other species in the wild include some surprising examples across the predator/prey divide. These have often been attributed to a mother losing her child and adopting the young of another species as a replacement, but Sædís is not known to have ever had a child of her own.
Nevertheless, orcas certainly take mothering seriously; members of one group having recently been found to sacrifice future breeding performance to go on raising sons throughout their lives.
The paper is published in the Canadian Journal of Zoology.