Where can 1.5 million penguins hide? In Antarctica, of course. But scientists tracked them down after they spotted scads of guano — penguin poop — on satellite images of an area where they had no idea such hordes existed.
The previously unknown mega-colonies of Adélie penguins were tracked to the Danger Islands, an archipelago of nine islands off the northern tip of the Antarctic Peninsula, according to a study published Friday.
The islands host 751,527 nesting pairs of Adélie penguins — more than the entire rest of the peninsula — and include the third and fourth largest Adélie penguin colonies in the world, according to the researchers.
The numbers were toted up by humans counting the birds on land, and via automated tallies of images taken by unmanned aerial vehicles.
Adélie penguins only live in Antarctica, and their population generally has been declining due to climate change and melting sea ice. But they seem to be faring better on the Danger Islands, which have more pack ice and extremely low ship traffic, the study notes. Based on aerial survey comparisons, the penguin population of the Danger Islands appears to have remained stable or even slightly increased over the last 60 years, according to the study.
The islands could continue to be a “hotspot for avian abundance,” according to the research paper, and therefore “deserve special consideration in the negotiation and design of Marine Protected Areas” in the region.
Counts of Adélie penguins in the area are critical because they’re “sentinel species” that help point the way to other climate change effects that are less easily measured, the study notes.
The organization’s goal is to build support for the largest protected area in the world: a 700,000-square-mile Antarctic Ocean sanctuary where industrial fishing would be banned. The international Commission for the Conservation of Antarctic Marine Living Resources says it will consider creating the sanctuary when it meets in Australia in October.
This article originally appeared on HuffPost.