It might sound like 1.5 million penguins are a hard thing to miss. However, that is indeed the case with this super-colony of Adélie penguins ( Pygoscelis Adeliae ) who have managed to remain undetected for decades in the Danger Islands of Antarctica. The remote, difficult to access, landmass, which lies off the continent’s northern tip, is always surrounded by thick ice. It was, therefore, believed to be uninhabitable and largely ignored by scientists.
However, in 2014, when Stony Brook University ecologist Heather Lynch was examining NASA satellite imagery of the islands, she noticed what appeared to be penguin guano or feces. Curious to investigate if the harsh terrain was harboring the torpedo-shaped flightless birds, Lynch planned an expedition with a team that included researchers from the Woods Hole Oceanographic Institution (WHOI), MIT, Oxford University, and Southampton University.
After several months of preparation, the researchers landed on the nine-island archipelago in December 2015. To their delight, they were greeted by hundreds of thousands of the nesting birds scattered across the chain that spans six miles across. To obtain a precise count, the researchers dispatched a commercial drone, which had been modified to operate in the extreme climate, to take images of the knee-high animals. A computer algorithm helped tally up the 751,527 penguin nests in the drone images. Based on the assumption that each nesting penguin had a mate out at sea, the researchers came to the conclusion that the islands are home to over 1.5 million specimens. The discovery is particularly exciting given that on the West Antarctic Peninsula, Adélie penguin numbers are dropping rapidly. With the new additions, scientists now estimate there are over four million known pairs of the birds, which sport a distinctive white circle around their eyes, in Antarctica.
“It’s a classic case of finding something where no one really looked! The Danger Islands are hard to reach, so people didn’t really try that hard,” said research team member Dr. Tom Hart from Oxford University.
In the study, published in Scientific Reports on March 2, 2018, the scientists said one of the things that surprised them about the newly-found penguins was their nesting habits. Unlike other Adélie penguins who nest in a circular pattern to protect against predators, the Danger Islands birds seem to have no such fear and prefer individual nesting spots. Thanks to the characteristic pinkish guano, the researchers know the penguins’ diet comprises primarily of shrimp-like krill. However, they are curious to investigate what makes the region productive enough to feed such a large population. One simple explanation, of course, could be the absence of fishing fleets which are kept at bay by the thick slabs of ice that surround the pristine islands.
“This exciting discovery shows us just how much more there still is to learn about this amazing and iconic species of the ice,” said Rod Downie, head of the polar programs at the World Wildlife Foundation (WWF). “But it also reinforces the urgency to protect the waters off the coast of Antarctica to safeguard Adélie penguins from the dual threats of overfishing and climate change.”
Unfortunately, the good news does not extend to all penguin species. King penguins, which can only breed on a few Antarctic islands, are threatened by rising ocean temperatures as their food sources move further away. Scientists estimate that the population could decline by up to 70 percent by 2100 if they are unable to find a suitable new habitat. Similarly, the population of chinstrap penguins, which get their name from the narrow black band under their head, has plummeted by more than half since 1986.
Resources: whoi.edu, independent.co.uk, smithsonianmag.com,sciencedaily.com