Moment killer whales hunt down dolphin before sharing the catch among themselves

A pod of killer whales have been spotted hunting down dolphin prey, before sharing the catch with their friends.

Photos show the moment the orcas attacking dusky dolphins in the Humboldt Current system, off the coast of Chile. The images came after years of surveillance by a team of scientists working to unveil the secrets of the little-known population.

The researchers, led by Dr Ana García Cegarra of the Universidad de Antofagasta, Chile, had previously seen the apex predators using fishing boats to help them capture sea lions. Now they have spotted them successfully hunting dusky dolphins for the first time - and sharing the food among the pod.

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Dr García Cegarra said: “Studying orcas in their natural environment is very challenging as they are marine top predators, travelling long distances and living offshore, which makes observation difficult. Understanding their role in the marine environment is crucial for the conservation of this poorly-known species in the Humboldt Current.”

Killer whales have a varied diet, but not all orcas eat the same things. Dr García Cegarra explained orca populations can be assigned to different ecotypes based on their preferred foods, acoustics, and genetics, so understanding what the Humboldt Current killer whales eat is a "major step" towards understanding where they fit in.

Observers saw the presence of orcas, group composition and location, and took pictures and videos which the scientists could cross-reference with catalogues of known individuals. By combining this data with their own systematic surveys and drone footage, the team built up a map of orca presence in the area and tracked pods’ behaviour and prey choices.

The research team say the sightings could indicate the Humboldt Current orcas may belong to the mammal-hunting Type A ecotype. Their prey, and their small pod sizes, would be consistent with the hypothesis, although their white eye patches are smaller than is typical of Type A orcas.

They have also never been recorded in Patagonia with other Type A orcas. Dr García Cegarra added: “We wish we could obtain skin biopsy samples to analyse their genetic data, as there is no genetic information for orcas in this region of the south-east Pacific. However, they are very elusive and intelligent, which makes it difficult to approach them in the boat for biopsies.

“The fact we have observed new-born calves is important, because it indicates they are having offspring, but we don’t know their survival rate. Thanks to citizen science, we can follow the presence of killer whales along thousands of kilometres of the coast of northern Chile - but most orca sightings are opportunistic.”