By Stephen Beech via SWNS
Killer whales have been spotted hunting down dolphins – and sharing the catch with pals – for the first time.
The dramatic new images of orcas in the Humboldt Current system, off Chile, show them preying on and eating dusky dolphins.
Scientists say the orca’s newly discovered hunting skills could help then protect the endangered species in the southern hemisphere.
Years of surveillance by a team of scientists are finally unveiling the secrets of the little-known population of orcas living in the Humboldt Current – including their eating habits.
The researchers, led by Dr. Ana García Cegarra of the Universidad de Antofagasta in Chile, had previously observed the orcas using fishing boats to help them capture sea lions.
But now they have spotted the apex predators successfully hunting dusky dolphins for the first time – and sharing the food among the pod.
Dr. García Cegarra says the new evidence of their eating habits may help experts understand how populations of orcas in the southern hemisphere are linked, promoting conservation efforts.
She said: “Studying orcas in their natural environment is very challenging as they are marine top predators, traveling long distances and living offshore, which makes observation difficult.
“But understanding their role in the marine environment is crucial for the conservation of this poorly-known species in the Humboldt Current.”
Killer whales are apex predators with a varied diet, but not all orcas eat the same things.
Dr. García Cegarra explained that 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.
Five different ecotypes are reported in the southern hemisphere: some, like Type A and Type B1 orcas, focus on marine mammals, while other types prefer fish.
The researchers say that understanding where the Humboldt Current animals fit in would help understand the way the populations relate to each other more broadly and conserve them for the future.
Dr. García Cegarra and her colleagues used a combination of their own surveys and citizen science data collection from whale-watching trips and fishing vessels to monitor the population and track their hunting habits.
Observers recorded the presence of orcas, group composition and location, and took pictures and videos which the scientists could cross-reference with catalogs 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’ behavior and prey choices.
That allowed the researchers to capture evidence of the Menacho pod of orcas catching dusky dolphins – a species no orcas in the area had ever been reported successfully hunting.
Dramatic images show the matriarch, Dakota, tossing a dusky dolphin into the air.
The research team says the sightings could indicate that 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 said: “We wish we could obtain skin biopsy samples to analyze 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 scientists’ observations of the dusky dolphin hunting, published in the journal Frontiers in Marine Science, also revealed that the Menacho pod were sharing their food.
Food sharing is recorded among many populations of orcas, sometimes to help feed kin, and sometimes because the pod hunts cooperatively and everyone gets a share.
The researchers suggest that the Menacho pod were sharing food with kin, similar to Type A orcas who hunt sea lions by deliberately stranding.
Female orcas were seen sharing meat with group members, allowing closer relations to eat first.
Dr. García Cegarra emphasized that more information and systematic study is necessary to fully understand and protect the Humboldt Current orcas.
She said: “The fact that we have observed new-born calves is important because it indicates that they are having offspring, but we don’t know their survival rate.”
Dr. García Cegarra added: “Thanks to citizen science, we can follow the presence of killer whales along thousands of kilometers of the coast of northern Chile – but most orca sightings are opportunistic.”
