杏吧原创

A long-finned pilot whale calf has been documented swimming behind the flipper of a female orca 鈥� in 鈥渆chelon鈥�, or the mother-and-calf position 鈥� for the first time. How the inter-species pair came together is unknown, leading researchers to wonder whether the calf was adopted or abducted.

In August 2021, a whale-watching tour near Snaefellsnes peninsula in West Iceland spotted a pod of three orcas with a surprise guest. at the West Iceland Nature Research Centre, who was on board, saw a young whale drafting off the wake of a female orca named Saed铆s, but the calf was too small to be an orca (Orcinus orca).

The youngster looked like a long-finned pilot whale (Globicephala melas), which puzzled Mrusczok, as no pilot whales were swimming through the area that afternoon. 鈥淚 knew what I was seeing 鈥� and I also saw it in the pictures 鈥� but my mind was just saying this cannot be. This is really, really weird,鈥� says Mrusczok. When she and her colleagues reviewed images and video footage later, they confirmed their suspicion: this was the first documented case of an orca showing parenting behaviour to a calf of a different species.

The bond appeared to be exclusive to Saed铆s and the calf. In the 21 minutes that Mrusczok observed the pod, the other two orcas didn鈥檛 interact with the young whale. The pilot whale鈥檚 visibly low body fat suggested it wasn鈥檛 nursing and was in poor health. Its still-wrinkled skin, called fetal folds, indicated that it was a newborn. When researchers saw Saed铆s the following summer, the calf was no longer with her, having probably succumbed to malnutrition, they say.

Both pilot whale and orca calves are used to being 鈥渂abysat鈥� for short periods while their parents hunt, says Mrusczok, which could increase the likelihood that they could latch onto a non-mother caretaker.

But calling this cross-species relationship parenting may be going too far, says at the University of Iceland, who wasn鈥檛 involved in the work. The young pilot whale may have been swimming near Saed铆s to draft off her wake and make swimming easier. 鈥淚t could be that the female is just tolerating the presence of this calf,鈥� says Samarra.

Over the decade that researchers have been watching Saed铆s, she has never had a calf of her own, and it is possible that she may have adopted the pilot whale calf as a substitute. 鈥淥ne theory is that it was an orphaned calf that they found and took into the pod,鈥� says Mrusczok. There could also be a more sinister explanation: this may be a case of calf-snatching.

When the two species cross paths in Icelandic waters each summer, pilot whales occasionally charge toward orcas to shoo them away. But in July 2022, a year after Saed铆s was seen with the calf, Mrusczok saw groups of both species make repeated advances toward each other in a way never before documented. This time, the orcas appeared to be the aggressors, charging a pod of pilot whales with multiple young calves. 鈥淭here is a possibility that the female [orca] that had the pilot whale calf before was trying to obtain another,鈥� says Mrusczok.

Whatever the cross-species custody arrangement is, it seems to be a trend. Samarra鈥檚 research team made a similar sighting in 2022. A different female orca in southern Iceland was swimming with a long-finned pilot whale at her side, which also looked malnourished.