A team of scientists has discovered a previously unknown massive "supercolony" of penguins in Antarctica by identifying dark guano stains in NASA satellite imagery. Following a visit to the site, the team used a specialized drone-assisted system to count the population, revealing a stunning 1.5 million Adélie Penguins.

The project began in 2014 when Heather Lynch from Stony Brook University and Mathew Schwaller from NASA identified dark stains on satellite imagery around an area at the northern Antarctic Peninsula tip called the Danger Islands. This specific region was not known to be an important penguin habitat but the satellite imagery suggested these dark spots were guano stains, pointing to a very large concentration of the flightless bird.

A larger team was recruited to travel to this notoriously inaccessible location in December 2015. Hundreds of thousands of penguins were immediately obvious on arrival, but a novel method of counting the animals was needed to get an accurate grasp of the population. Using a commercial quadcopter drone the count began, utilizing custom imaging and navigation technology developed by Hanumant Singh from Northeastern University.

"The drone lets you fly in a grid over the island, taking pictures once per second. You can then stitch them together into a huge collage that shows the entire landmass in 2D and 3D," says Singh.

Once mapped, a computer analyzed the images pixel by pixel to accurately calculate the population. The system found a stunning 751,527 pairs of Adélie penguins. As well as being the largest population of this species of penguin on the Antarctic Peninsula, these animals seem to have not suffered the same decline in numbers seen in similar populations on the opposite, western side of the peninsula.

"The population of Adélies on the east side of the Antarctic Peninsula is different from what we see on the west side, for example," says Stephanie Jenouvrier, a seabird ecologist working on the study. "We want to understand why. Is it linked to the extended sea ice condition over there? Food availability? That's something we don't know."

A comprehensive study of aerial and satellite imagery of the area from up to 60 years ago suggests that this population of penguins has remained stable in the region for over half a century. The research adds more weight to arguments to institute a proposed Marine Protected Area near this stretch of the Antarctic Peninsula.

The research was published in the journal Scientific Reports.

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