The first documented case of cooperative hunting between killer whales and dolphins has been observed in the waters off British Columbia, Canada. Incredible aerial footage shows the two species sharing fish scraps after a kill, and scientists have some theories as to why they’re teaming up.
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The cetaceans in question include a pod of northern resident killer whales, Orcinus orca, who share their hunting grounds with Pacific white-sided dolphins, Lagenorhynchus obliquidens. They compete for the same resources, and yet they’re regularly seen swimming within meters of each other while fishing along the coastline of British Columbia.
Typically you’d expect to see some signs of conflict when two predatory species share territory, and yet nobody’s ever seen them fighting or avoiding each other. It got scientists wondering if, in fact, they might be in cahoots.
To find out, they tracked the movements of nine northern resident killer whales while on the lookout for any interactions with Pacific white-sided dolphins. The monitoring took place back in 2020 around Vancouver Island and collected movement and acoustic data along with aerial and underwater footage (which was captured using cameras strapped to the killer whales themselves).
Those datasets revealed 25 interactions where the killer whales came across dolphins and changed direction in order to follow them. Together, they embarked on foraging dives – so why team up when it’s surely better to enjoy the spoils all to yourself?
The scientists reckon killer whales benefit from the dolphins’ quieter approach to locating Chinook salmon (Oncorhynchus tshawytscha). The dolphins may be letting them tag along because these salmon are too large for them to consume whole, and killer whales are very good at chomping things into bitesize pieces.
It’s also possible the killer whales are a kind of protection for the dolphins who would otherwise be more vulnerable to attack from other pods of killer whales that pass through the area. Better the devil you know, after all.
This was supported by four recorded instances of the killer whales sharing dismembered salmon between their pod while dolphins were present. There was also one occasion where dolphins were seen scavenging salmon remains from the orca, which is known as prey-sharing.
“[O]ur data suggest that interspecific cooperative foraging offers ecological advantages to both species, particularly during seasonal Chinook salmon migrations when prey is more concentrated but also more evasive,” conclude the authors. “Whether this behavioural pattern persists during other seasons or in the absence of high-value prey remains an open question and warrants further investigation.”
Prey-sharing isn’t unusual at all among animals of the same species, but the authors believe this to be the first documented case of cooperative hunting between killer whales and dolphins. It’s an exciting glimpse into a previously unrecognized relationship, but further research is needed before we can be confident about the motivations behind this cetacean power couple.
The study is published in the journal Scientific Reports.
Source Link: Killer Whales And Dolphins Team Up In First-Ever Footage Of Cooperative Hunting
