Emperor penguin colonies are not easy to find: Their breeding grounds are remote, icy expanses, that are unobservable at distances greater than just a few kilometers due to the curvature of the Earth.

So scientists who want to monitor how these birds are faring in an unstable environment have had to come up with inventive ways of spotting them. One effective option: Penguin guano stains, as viewed from space.

In 2009, researchers published a paper identifying 10 new penguin colony locations based on satellite images of "faecal staining."

"We can't see actual penguins on the satellite maps because the resolution isn't good enough. But during the breeding season the birds stay at a colony for eight months. The ice gets pretty dirty and it's the guano stains that we can see," Peter T. Fretwell, one of the paper's authors, told the Guardian at the time. In addition to the 10 new colonies, they were also able to confirm or revise the locations of 26 previously known colonies as well.

Now one of those 10 colonies has received its first human visitors. In December, a team of Belgian and Swiss explorers traveled by snowmobile and foot 30 miles from their base on the Derwael Ice Rise, where they are studying ice loss. They arrived at the colony around midnight (still light out in Antarctica at that time of year) and were stunned to find thousands upon thousands of penguins, some 9,000 or 10,000 all told, depending on who's counting.

"It was almost midnight when we succeeded in finding a way down to the ice through crevasses and approached the first of five groups of more than a thousand individuals, three quarters of which were chicks. This was unforgettable moment," Alain Hubert, the expedition's leader, said in a statement.

On NPR, Hubert described that moment to host Neal Conan (worth listening to in full), "After a few minutes, you have those penguins, you know, just comes to say hello and to look at you, because they are the local population. We are not." The guano, Hubert told Conan, doesn't smell — it's too cold. But, he reports, "I spoke to some scientists that and they told me, if it was a bit warmer, it's really smelly."

Pictures from the expedition capture that moment of first contact and more are available on Hubert's website.

Images courtesy of Global Ecology and Biogeography and International Polar Foundation

This article originally published at The Atlantic here