It is also the only island to date with a population estimate (285,000-305,000) derived from a ground survey of the island.
In fact, scientists had believed the penguin population on the continent was in severe decline, thanks to changing weather and sea ice patterns, which had led to the loss of at least eight Adélie penguin colonies.
Heather Lynch, an associate professor of ecology at Stony Brook University, found guano stains on satellite imagery of the Danger Islands (yes, really). "In the Antarctic, distances are so vast, something major could be just around the corner and you wouldn't know".
The duo teamed with ecologists from Woods Hole Oceanographic Institution and other universities in the U.S. and United Kingdom for an expedition in 2015.
"We thought, 'Wow! If what we're seeing is true, these are going to be some of the largest Adélie penguin colonies in the world, and it's going to be well worth our while sending in an expedition to count them properly". That's more than the rest of the Antarctic Peninsula combined. The existence of the supercolony could bolster support for Marine Protected Areas around Antarctica. Piecing the photos together later, they were able to clearly count the black back of penguins atop nests in comparison to the light-colored land below them. He then realized that he had discovered a hidden penguin colony.
"The population of Adélies on the east side of the Antarctic Peninsula is different from what we see on the west side, for example", said one of the authors, Stephanie Jenouvrier from the Woods Hole Oceanographic Institution.
Animals inhabit rocky archipelago called risky island.
Dr. Tom Hart told BBC News: "It's a classic case of finding something where no-one really looked!"
"We want to understand why".
Even in the austral summer, the ocean surrounding the archipelago is filled with the kind of thick sea-ice that ships try to avoid. "We all knew there would be a lot penguins there, but I think none of us knew there would be this many". "Given that MPA proposals are based in the best available science, this publication helps to highlight the importance of this area for protection", she says.