An unprecedented study has documented the initial evidence of orcas and Pacific white-sided dolphins working together to hunt salmon in the waters of British Columbia.
Surprising Allies in the Hunt
The research, released in a scientific journal, suggests that interactions between northern resident orcas and marine mammals are far more than random occurrences while searching for food.
"These predators are expert salmon hunting professionals. To see them following dolphins as though they were guides was truly unexpected – and really exciting," said the principal researcher.
Extensive evidence, including drone video, acoustic recordings, and submarine video, guided scientists to determine the two predators are functioning as a coordinated team.
The Strategy Unfolds
Video footage from the research depicts the aquatic mammals – which serve as "scouts" – moving effortlessly through the water in pursuit of sizeable Chinook salmon. The orcas follow closely behind.
When the orcas catch their prey and dismember them at the surface to distribute with others, the smaller cetaceans collect the leftovers.
Interestingly, the predators, which are usually highly defensive of freshly hunted food, seem unbothered by the dolphins' presence.
Investigating the Reasons
Scientists considered several explanations for this close proximity and the lack of aggression from the larger predators.
- Safety Hypothesis: One idea was that the smaller mammals were merely obtaining protection from other predators by staying near the whales.
- Hydrodynamic Hypothesis: Another suggestion was that the animals benefited by bow riding the orcas, which decreases water resistance.
- Kleptoparasitism: The researchers also weighed the possibility that the dolphins were just stealing scraps of food.
"If the animals were parasites, just there for a free lunch, the whales might act aggressively... But we truly didn't see evidence of conflict between them. And that genuinely surprised us," explained the lead researcher.
That finding left the final explanation: the two hunters were engaging in teamwork.
Advanced Study Methods
To closely examine the predatory behavior, researchers used a specialized tag attached to the whales. This equipment recorded video, sounds, dive data, and vocalisations.
Because the dolphins were so nearby, the devices often detected the vocalisations of the two mammals.
"There was this alternating pattern, where our tagged whale would echolocate, and then there'd be a period of silence, and then we'd hear dolphin echolocation clicks," said the researcher. "This raises a question: are both species hearing each other? Are they sharing information?"
Broader Implications
The simultaneous use of echolocation by the two species suggests the possibility they could collectively increase their acoustic field of view, making the hunt more efficient.
The research group said more study is needed to understand the full extent of the benefits for both species.
"Could it be there is something beneficial for both dolphins and the orcas?" pondered the researcher. "Are orcas that partner with dolphins end up better at foraging than those that hunt without?"
In conclusion, the findings has reshaped the perception of what these highly intelligent marine animals are capable of.
"Observing them likely cooperatively hunting with a different creature demonstrates how adaptable they are to evolving and refining their hunting strategy," the scientist summarized.
