Emperor penguin populations are notoriously difficult to track, as they spend warm months at sea and brutal Antarctic winters on land. But scientists with the British Antarctic Survey (BAS) have found a new way to monitor colonies: tracking satellite images of their guano (poo) stains, which are visible from orbit. The maps don't pick out individual penguins, but "during the breeding season the birds stay at a colony for eight months," Peter Fretwell, a geographic information expert at BAS, said in a statement. "The ice gets pretty dirty and it's the guano stains that we can see." The new survey, published in the current issue of Global Ecology and Biogeography, found a total of 38 colonies around the continent—10 of which hadn't been identified before. Here, penguins and a patch of guano-stained ice near the BAS's Halley Research Station.