A Mysterious Group of Orcas Near Chile has Been Found, Revealing New Hunting Techniques

Off the coast of Chile, in the krill- and anchovy-rich waters influenced by the Humboldt Current, resides a rarely seen population of orcas. Through citizen science and years of diligent monitoring, a research team led by Dr. Ana García Cegarra from the Universidad de Antofagasta is beginning to uncover their mysteries—starting with their feeding habits.

García Cegarra’s team, who had previously seen these orcas using fishing boats to catch sea lions, recently observed them successfully hunting dusky dolphins for the first time and sharing the catch within the pod. This new insight into their diet could help scientists better understand how orca populations in the southern hemisphere are connected, aiding conservation efforts.

“Studying orcas in their natural habitat is challenging since they are top marine predators that travel vast distances and live offshore, making observation difficult,” said García Cegarra, lead author of the study published in Frontiers in Marine Science. “However, understanding their role in the marine ecosystem is essential for conserving this little-known species in the Humboldt Current.”

Ecotypes and Dietary Diversity

Orcas are top predators with diverse diets, but not all orca groups eat the same prey. They can be categorized into different ecotypes based on their preferred food, vocalizations, and genetics. Understanding what orcas in the Humboldt Current consume is a significant step in determining how they relate to other orca populations worldwide.

In the southern hemisphere, five distinct ecotypes are identified. Some, like Type A and Type B1, primarily hunt marine mammals, while others prefer fish. Learning where the Humboldt Current orcas fit in will provide insight into how these populations are interconnected and help with future conservation efforts.

García Cegarra and her team used a combination of their own research and data collected by citizen scientists on whale-watching tours and fishing boats to study the orca population and their hunting behavior. Observers documented orca sightings, group compositions, and locations, capturing photos and videos that researchers matched with existing individual identification catalogs.

By integrating this information with their own systematic surveys and drone footage, the scientists created a detailed map of orca presence in the region, tracking pod behaviors and prey preferences.

Menacho Pod’s Remarkable Dusky Dolphin Hunt Captured on Camera

This enabled researchers to document the Menacho pod of orcas hunting dusky dolphins—a feat never before observed in this region. Striking images show the pod’s matriarch, Dakota, hurling a dusky dolphin into the air.

These observations suggest that these orcas might belong to the mammal-hunting Type A ecotype, as their prey choice and small pod sizes align with this classification. However, their smaller white eye patches differ from the typical Type A appearance, and they have not been seen in Patagonia alongside other Type A orcas.

“We hope to collect skin biopsy samples for genetic analysis, as there is no genetic data for orcas in this part of the southeast Pacific,” said García Cegarra. “But they are elusive and intelligent, making it challenging to approach them for biopsies.”

The researchers also observed the Menacho pod sharing their dusky dolphin catch. Food sharing is common among orca populations, often serving to feed relatives or distribute food after cooperative hunts.

In this instance, García Cegarra and her team believe the pod was sharing with close kin, similar to the behavior seen in Type A orcas when hunting sea lions. Female orcas were observed distributing meat, with close relatives eating first.

García Cegarra stressed the need for more systematic studies to fully understand and protect this elusive orca population.

“Observing newborn calves is significant, as it shows they are reproducing, but we don’t know their survival rates,” she noted. “Citizen science helps track orca presence along thousands of kilometers of northern Chile’s coast, but most sightings are still opportunistic.”

Read the original article on: Phys Org

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