Hector’s dolphins, the world’s smallest marine dolphins, are only about 1.4 meters long, but new research has revealed they are far more acrobatic and adventurous than anyone realized.
For years, scientists watching from boats could only guess what these rare dolphins were doing underwater.
Now, thanks to high-tech tracking devices, a hidden world of flips, deep dives, and clever hunting strategies has been uncovered.
The study, published in Conservation Letters, shows that Hector’s dolphins are capable of dramatic underwater barrel rolls, swimming upside down near the sea floor, and diving to surprising depths—up to 120 meters.
“There are some seriously impressive dives,” said Dr. Ilias Foskolos, a marine scientist at the University of Auckland and lead author of the study. “For an animal just 1.4 meters long, going down to 120 meters wasn’t what we expected at all.”
To capture these secret behaviors, the researchers used DTAGs—sound and movement recording devices developed by Professor Mark Johnson.
The small tags, attached to 11 dolphins with suction cups, recorded both the dolphins’ motion and the sounds they made while hunting. The study was carried out in the Clifford and Cloudy Bay Marine Mammal Sanctuary at the northern tip of New Zealand’s South Island.
The recordings revealed fascinating details about how the dolphins change their hunting tactics depending on where they are feeding.
Near the seabed, they slowed down and swam upside down to snatch flatfish and cod from the sand. In midwater, they became more energetic, performing spinning barrel rolls to catch fast-moving schools of fish.
The dolphins even produced distinct sounds while chasing prey: their echolocation clicks turned into a buzzing noise, almost like a power drill, when they zeroed in on a target.
The research also tracked how far the dolphins traveled. One was recorded swimming 15 kilometers offshore, farther than expected for a species usually seen close to the coast.
According to Professor Rochelle Constantine of the University of Auckland, the results highlight how important these tracking devices are for studying dolphin behavior.
“Even though this is a preliminary study, the DTAGs have shown us how these dolphins dive, feed, and move in their habitat,” she explained. “This information is crucial for understanding how to reduce risks like entanglement in fishing gear or collisions with boats.”
Hector’s dolphins are found only in the coastal waters around New Zealand’s South Island, with a population of about 15,000. Marine Mammal Sanctuaries and government protection plans aim to manage the overlap between human activity and dolphin habitats.
The new insights from this study will help strengthen these efforts, ensuring the tiny but remarkable dolphins can keep performing their barrel rolls and deep dives for generations to come.
