In case you weren’t already impressed with the fortitude of Antarctica’s iconic resident species, the emperor penguin, a new study in the journal Marine Ecology Progress Series reveals that they can stay underwater for as long as 32.2 minutes. For reference, most humans start feeling light-headed after 30 seconds.
The data, collected after lead author Kim Goetz and her colleagues fit 20 emperors with satellite-enabled tracking collars, shatters the previous record of 27.6 minutes. In addition to dive duration, the 96,000 separative dive events recorded before the collars fell off showed that the birds regularly plunge 90 meters (295 feet) deep in search of food; occasionally venturing as far as 450 meters (1,480 feet).
Amazingly, these unprecedented findings are the serendipitous outcome of a scientific plan gone awry. Goetz and her team first set out to Antarctica in 2013 with the intention of tagging breeding emperors in January, after the birds have completed the stressful molting process, but the ship was waylaid on its route south. The New Zealand-based team ended up arriving at Cape Colbeck in March, when freshly re-feathered individuals have typically headed back to the eastern Ross Sea to fatten up in preparation for the next breeding cycle.
“We didn’t expect penguins to still be there and thought we would have to locate them on the pack ice which was going to be more difficult,” Goetz said in a statement.
But in reality, they encountered a handful of emperors who were lazing around, delaying their departure from the comfort of the solid ice-covered shelf because, as non-breeding individuals, they needn't hurry back in time for the next season.
Realizing that they had a unique opportunity to study the species during a phase of their life cycle that humans rarely witness, and that coincides with the harshest environmental conditions of the year, Goetz and company switched gears and tagged the stragglers.
When analyzing the collars’ incoming transmissions over the next six months, the researchers quickly realized that the penguins’ dives varied according to their proximity to the Antarctic continental shelf.
Dives within the shallower water of the shelf tended to be short, likely because the birds were able to forage for krill and other pelagic invertebrates. Dives in the open sea, on the other hand, were deeper, longer, and characterized by more rapid movements, reflecting a hunt for fish.
Goetz and her team also learned that the non-breeding penguins migrated much farther north than anticipated – up to 9,000 kilometers (5,600 miles) away from the colony grounds – during the southern hemisphere winter, a behavior that could reflect an adaptation to melting sea ice.
"That’s why understanding their entire life cycle, especially when birds are not restrained by chick-rearing duties, is critical to predicting how emperor penguins might respond to environmental changes," Goetz concluded.
