A previously unknown “supercolony” of more than 1.5 million penguins in the Antarctic peninsula was discovered by a team of researchers led by the Woods Hole Oceanographic Institution on Cape Cod, who spotted the penguins on satellite imagery.

The findings, published in the journal Scientific Reports on Friday, reveals a small chain of remote islands known as the Danger Islands to be a habitat for Adélie penguins, a species that biologists previously believed to be declining, according to a statement from WHOI.

“Not only do the Danger Islands hold the largest population of Adélie penguins on the Antarctic Peninsula, they also appear to have not suffered the population declines found along the western side of Antarctic Peninsula that are associated with recent climate change,” Michael Polito, researcher and assistant professor of oceanography at Louisiana State University, said in the statement.


Researchers first noted feces stains in satellite imagery of the Danger Islands, which led them to believe there was “a mysteriously large number of penguins,” WHOI said. So, the team launched an expedition to the islands in December 2015 to see if they were right.


They discovered thousands of birds resting in rocky soil and took population tallies by hand and with the use of a drone.

“The drone lets you fly in a grid over the island, taking pictures once per second,” Hanumant Singh, an engineering professor at Northeastern University who developed the drone’s imaging system. “You can then stitch them together into a huge collage that shows the entire landmass in 2D and 3D.”

Researchers believe the penguins were undiscovered for so long because of how remote the islands are, as well as being surrounded by thick sea ice and treacherous waters, WHOI said.

In the future, researchers want to study how the penguin population is distributed on the peninsula and why, including looking at ice condition and food availability. They believe knowledge of the penguin colony could also support proposed marine protected areas.


Adélie penguins nesting on the Danger Islands.
Adélie penguins nesting on the Danger Islands.MICHAEL POLITO/AFP/Getty Images
An aerial view of an Adélie penguin breeding colony on Heroina Island in the Danger Islands.
An aerial view of an Adélie penguin breeding colony on Heroina Island in the Danger Islands.THOMAS SAYRE-MCCORD/AFP/Getty Images

Laney Ruckstuhl can be reached at laney.ruckstuhl@globe.com. Follow her on Twitter @laneyruckstuhl.