Scientists have made significant progress in understanding a little-known population of orcas off Chile’s coast, with first-time documentation of the orcas hunting dusky dolphins.
An orca identified as “Dakota”, the matriarch of a pod found off Chile, tosses a dusky dolphin into the air. (Photo credit: Maikol Barrera / CC BY 4.0)
These orcas, living in the krill- and anchovy-rich waters of the Humboldt Current, have previously been observed using fishing boats to help them capture sea lions. Now, they have been observed to be skilled hunters of dusky dolphins, a behavior documented for the first time by a team led by Dr Ana García Cegarra of the Universidad de Antofagasta. The findings reveal that the orcas share their prey within their pods, suggesting complex social behaviors and shedding light on their ecological role.
Orcas are apex predators, but their diets vary by ecotype—groups defined by diet, genetics and acoustics. In the southern hemisphere, five ecotypes are recognized, with some, like Type A and Type B1, specializing in marine mammals, while others focus on fish. The Chilean orcas’ preference for mammal prey, like dusky dolphins, aligns them with the Type A ecotype. However, their distinctively small eye patches and absence from Patagonia—a known Type A habitat—suggest that they may differ from typical Type A populations.
Citizen science and monitoring
Dr García Cegarra’s team combined citizen science contributions from whale-watching trips and fishing vessels with systematic surveys and drone footage to build a comprehensive profile of these orcas. Observers documented group composition, location and behavior through photos and videos, which the scientists cross-referenced with catalogs of known individuals. This collaborative approach enabled the team to map the orcas’ presence and identify prey preferences.
Hunting behaviors and food sharing
The team recorded evidence of the Menacho pod, led by a matriarch named Dakota, successfully hunting dusky dolphins. Striking images captured Dakota tossing a dolphin into the air, marking the first time such behavior has been observed in this region. This discovery expands understanding of their hunting capabilities and ecological niche.
The Menacho pod was also observed sharing the spoils of their hunt. Female orcas distributed meat to group members, prioritizing closer kin, a behavior seen in other mammal-hunting orcas, including Type A. Such cooperation strengthens bonds within the pod and ensures survival through shared resources.
Conservation implications
These findings help clarify the ecological role of Humboldt Current orcas and their connections to other populations. Understanding their diet and behaviors is critical to advancing conservation efforts and protecting this unique population in a rapidly changing ocean environment.
“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,” said Cegarra, lead author of the study in Frontiers in Marine Science. “But understanding their role in the marine environment is crucial for the conservation of this poorly-known species in the Humboldt Current.”
