Scientists counting emperor penguins from space have found twice as many of the birds in Antarctica as expected.
Using high-resolution satellite images to study each of 44 colonies around the coastline of Antarctica, experts said they put the total emperor penguin population at 595,000, or roughly double previous estimates of 270,000 to 350,000. Seven of the colonies studied had never been seen before.
A key advantage of satellites is that they can capture multiple images in one go, whereas visiting dozens of remote colonies in temperatures as low as -50 degrees Celsius would be hugely expensive and time-consuming.
Still, conducting a penguin roll-call from space is not simple. It took a special technique known as pan-sharpening to increase the resolution of the satellite images to differentiate between birds, shadows and penguin poo, or guano.
While some images remained tricky to analyze, Peter Fretwell, the team leader of the British Antarctic Survey, believes the overall population figure is correct to within a 10-12 percent margin of error.
The study by Fretwell and colleagues, published in the online journal PLoS ONE, marks the first time that researchers have counted the entire population of any species by satellite.