Something unusual has been going on in the wild. Many members of the largest species of dolphins, commonly called killer whales (Orcinus orca), have been found sharing freshly killed prey with humans.
And they don’t just offer their prey: the dolphins have waited for the humans to respond.
In a new study reported in the JournalofComparativePsychology, researchers have investigated why these killer whales have been provisioning humans. The study stemmed from the authors’ own experiences of provisioning.
Waterworld data
While killer whales are known to be prosocial animals and among the few that share prey both among themselves and across species, they rarely interact with humans.
“I’ve experienced killer whales offering me prey on more than one occasion, which provided the initial motivation for the study,” said Jared Towers, a marine biologist and executive director of the Bay Cetology research institute in British Columbia, Canada.
The team collected data from the period 2004-2024 from five ocean parts: Eastern North Pacific, Eastern Tropical Pacific, Western South Pacific, Western South Atlantic, and Eastern North Atlantic. The information came in the form of interviews, plus photos and videos where they were available. The team also made note of whether the killer whales had released their prey, how far they kept from the humans, and whether they waited for the humans to respond.
The team included only those instances in their analysis where the human observers were a significant distance from the killer whales before the animals approached. For example, the criterion for humans underwater at the time of provisioning was that they had to have been at least 15 m away from the killer whales before an interaction. The animals would then have approached to within their own body length and released their prey in front of their bodies.
How’s she feeling?
Of the 34 instances the team was able to finalise, the killer whales awaited a human response before they recovered or abandoned the offered prey and retreated in 33 instances. Their offering included diverse species such as seaweed, invertebrates, fish, reptiles, birds, and mammals. Some people also reported that they didn’t accept the offering at first. Towers was one of them: “I didn’t accept the offerings because it was a shock when it happened. And there’s only a few seconds to decide what to do. Easier just to observe.”
Like humans, killer whales are at the top of their respective food chain. They also have high levels of encephalisation, meaning a larger brain size relative to the size of the body, over evolutionary time. Research has linked high encephalisation to better cognition, learning, and social behaviour.
These animals live and hunt in groups led by a matriarch, the oldest female, and the group’s behaviour largely depends on the matriarch.
“If she tends to be curious and friendly, that’s the way the whole group is. Sometimes it works for, sometimes against the killer whales,” Robert Pitman, a marine ecologist at the Marine Mammal Institute Affiliate at Oregon State University, said.
Dolphins are smart
Some experts have said that the killer whales might be playing. However, this activity is usually associated with juveniles whereas the new study found adults and juveniles alike to have been provisioning humans. Animals also play only when their own nutritional needs have already been met.
The study, however, found that in half of all the instances, the killer whales were offering whole prey, not partly eaten. When humans rejected or refused the animals’ offering, they shared the prey with other killer whales in 76% of the cases.
For these reasons, the authors said, the killer whales may have been exploring, not playing.
Animals mainly explore their surroundings to reduce uncertainty about their physical, social, and/or environmental surroundings. Exploration is technically the conscious pursuit of knowledge — and a reflection of the dolphins’ evolved intelligence.
An orcan science
In a few instances when humans tossed the prey back to the killer whales, they immediately reciprocated, suggesting they were learning what humans preferred.
“Some of these things are associated with play, but some of these things may also be defined as scientific thinking, which has been described as the ability to ask questions and then pursue answers,” Towers said.
Then again, while the animals’ behaviour appeared to be prosocial and altruistic, the researchers warned that it could be Machiavellian behaviour as well, i.e. marked by manipulative or deceptive actions for personal gain. Killer whales have been known to behave in this way to steal fish from fishing lines and to damage vessels.
“Some of these cases may be Machiavellian because killer whales often act without due regard for people, even though they have not harmed anyone in the wild,” Towers said.
A citizen science
Even if most of the study’s observations are anecdotal and recorded by amateurs, Pitman said, many such citizen science projects have allowed enthusiasts to make legitimate contributions to science.
“If you’re trying to document a very rare event, that is a challenge in itself,” he added. “Plus, citizen science allows you to do things that you couldn’t, like significantly increasing your sample size.”
As humans and killer whales interact more and more, the dolphins are likely to adapt their behaviour to become more friendly or more hostile, depending on the female leading the group. Then again, these interactions could pique human curiosity about killer whales and potentially improve conservation efforts.
“People are often inclined to conserve or protect the things they relate to and care about. In this case, we have experienced killer whales going out of their way to relate to us,” Towers said.
Rohini Karandikar is a science communicator, educator and facilitator, and currently works with the TNQ Foundation.
Published – September 01, 2025 05:30 am IST
