Scientists were recently stunned to discover that more than 1,500,000 Adelie penguins have been living in obscurity on the Danger Islands off the Antarctic Peninsula's northern tip.
For the past 40 years, the total number of Adelie Penguins, one of the most common on the Antarctic Peninsula, has been steadily declining - or so biologists have thought.
The penguins managed to go undetected for so long because the islands where the birds live are so hard to access that, even in the summer, ice-filled waters surrounding the islands make human visits too treacherous. Even in the austral summer, the nearby ocean is filled with thick sea ice, making it extremely hard to access.
In a new paper in the journal Scientific Reports, scientists with the Woods Hole Oceanographic Institution (WHOI) explain how they managed to spot the birds after noticing unusually large patches of excrement in images of the islands taken by NASA satellites, in 2014.
Researchers arranged an expedition to the islands with the goal of counting the birds firsthand.
Using multiple simultaneous counts on the ground, quadcopter-based aerial photography and high-resolution satellite imagery they found that the Danger Islands have 751,527 pairs of Adélie penguins, more than the rest of the entire Antarctic Peninsula region combined.
"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.
"The results of our study indicate that 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 populations declines found along the western side of Antarctic Peninsula that are associated with recent climate change", Polito said.
"The population of Adélies on the east side of the Antarctic Peninsula is different from what we see on the west side, for example". We want to understand why.
"The size of these colonies makes them regionally important and makes the case for including them in the proposed Weddell Sea Marine Protected Area", said Tom Hart, a researcher at Oxford's Department of Zoology and co-author of the study.