How do you hide 1.5 million penguins? You put them on the remote and hard-to-access Danger Islands in the Antarctic, far from human eyes. And how do you find 1.5 million penguins? You spot a whole lot of telltale penguin poop in NASA satellite imagery.

Researchers thought the overall Adélie penguin population had been in decline for decades, but they've now discovered a secret stash of the photogenic seabirds. 

It all started in 2014 when Stony Brook University Professor Heather Lynch and NASA scientist Mathew Schwaller found evidence of guano stains in NASA satellite views of the Danger Islands. Where there is lots of poop, there are probably lots of penguins.

A 2015 expedition discovered a massive number of birds. The team counted them up with an assist from a quadcopter drone. The drone snapped photos of the island, which the team stitched together to get an accurate penguin count. 

The team published its findings online Friday in the Scientific Reports journal. It now calls the Danger Islands a "seabird hotspot." 

"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 population declines found along the western side of Antarctic Peninsula that are associated with recent climate change," says study co-author Michael Polito, a marine biologist at Louisiana State University.  

The Woods Hole Oceanographic Institution says the supercolony discovery supports the need to protect the area around the Antarctic Peninsula.

Woods Hole also released a video showing the drone's eye view of part of the supercolony and it looks almost unreal.