Scientists have historically had a hard time studying how gentoo penguins communicate with each other in the icy waters they hunt in off Antarctica.
To eavesdrop on this communication, scientists from the Korean Polar Research Institute (KOPRI) strapped the penguins with small video cameras that had built-in microphones. Their results, published in the journal Nature, are providing insights on how these iconic birds live.
They found that gentoo penguins seem to call to each other to form groups, but it's unclear what the groups' exact functions are. (Elephant seals can recognize their rival's call—hear them here.)
Over the course of two Antarctic summers, 26 individual penguins were strapped with cameras, eventually recording 598 penguin call events. Footage showed that after particular calls, the penguins were observed moving in unison and swimming near the surface.
The video above reveals the small birds bobbing in and out of the water before diving below the surface. After emitting several, low calls, a penguin dives under water, joining a large group of gentoos.
Gentoo penguins typically spend most of their days hunting close to shore, but they're known to swim as far as 16 miles out to sea and dive nearly 655 feet below water to find food (from fish to krill). The study noted that it's unlikely the calls are used to alert members of the hunting groups to predators (such as leopard seals), as those animals usually congregate near the shore, and the calls were made in open ocean.
The short calls heard before the penguin dives under the water resemble some of the contact calls used by African penguins. Researchers believe the calls are used to assemble these groups by attracting other penguins. Even more remarkable, nearly half of the gatherings occurred within a minute after the call was made. Penguins that made the calls spent less time underwater, perhaps because the vocalizations require energy.
How the penguins communicate back-and-forth couldn’t be easily discerned (the microphone was muffled by the penguins' backs), but the study suggests penguins could be vocally interacting. (Read about what happened when a male penguin found his mate with another male.)
The study's authors hypothesized that gentoo penguins likely form groups to improve their chances at catching food in some way, which is not yet understood. It's also unclear what the calls' exact functions are. An eight-hour time recording limit on the camera and limited visibility in the water made assessing interactions difficult. However, the team hopes to investigate further by placing cameras on multiple penguins in the same group.