"We were. very lucky to have a window of time where the sea ice moved out and we could get a yacht in", said Lynch.
Heather Lynch, a professor of ecology and evolution at Stony Brook University, in NY, and Mathew Schwaller from NASA, spotted guano stains in images of the Danger Islands, off the northern tip of the continent.
Dr Tom Hart, of Oxford University, one of the expedition party, told The Daily Telegraph: "This is the biggest colony discovered recently".
What's more, the number of penguins on the Danger Islands - which are farther north and closer to the icy Weddell Sea - appear to have remained stable over the decades.
Members of the expedition team arrived at the island in December 2015.
Researchers involved with the project said the drone technology has been key because it will provide insight on penguin dynamics and the effects of climate change.
Using a Quadcopter drone, the researchers flew a grid pattern across the islands, taking multiple photos of the birds and their nests.
However, in 2014, while analysing Nasa's existing satellite images of the islands, Lynch and Nasa's Mathew Schwaller found tell-tale poop stains, indicating the presence of a mysteriously large number of penguins in the area. Once those huge pictures are accessible, he says, his group can utilize neural system programming to break down them, pixel by pixel, scanning for penguin settles self-sufficiently. Up until now, there were fears the penguin species was declining rapidly due to climate change.
Now it turns out, the area may need stronger protection from overfishing.
Polito said earlier studies have indicated that less than 1 percent find other locations to build nests.
"We want to understand why".
The geography of the islands explains how these penguins, whose distinguishing features are the white rims around their eyes, have survived without detection: even in summer, the area is so "socked in with sea ice that it is very hard to get a ship through", Lynch also told the WSJ. And now that the colony's secret is out (admittedly a human-centric point of view), the scientists would like to see the mega-colony's habitat designated as a protected marine area. Polito said the publication of their study comes at just the right time to assist in that effort, as an global body that oversees Antarctica's wildlife resources is expected to review new refuge proposals in October. "Food availability? That's something we don't know", said Stephanie Jenouvrier, a seabird ecologist at WHOI, in a press release.