Alain Hubert slowly made his way down an icy crevasse on Antarctica’s Princess Rangnhild Coast to a large plain of snow and ice early last month.
Spread across the frozen tundra before him, 9,000 members of a never-before-visited colony of emperor penguins huddled together for warmth against the subzero temperatures of the world’s coldest continent.
Hubert, a Belgian expedition leader and engineer for the Princess Elisabeth Antarctica Polar Research Station, says he decided to go looking for the emperor penguin colony after coming across a satellite map estimating its location. “I had noticed individual penguins along the coastline for years but had never come across a colony,” Hubert says. “It was a miracle finding it in an area that is almost entirely unexplored.”
Scientists with the British Antarctic Survey (BAS) first uncovered evidence of the colony back in 2009 while scanning the white snow and ice of Antarctica by satellite. They noticed strange brown splotches they couldn’t initially identify. “After a while, we came to the conclusion that it was guano from an emperor penguin colony,” says Phil Trathan, head of conservation biology for the survey group. “We said ‘Hey, if we can see this one, we can see others.’”
The BAS team located Hubert’s colony as well as six other previously unknown emperor penguin colonies that year. Since then Trathan and fellow BAS researchers have been busy locating and estimating the full population count of emperor penguins across Antarctica using the satellite scanning technique. Survey geographer Peter Fretwell says the team uses low- to medium-resolution satellite cameras to find distinctive brown regions of snow and ice that are evidence of a colony. Next, high-resolution cameras and a technique called pan-sharpening help to enhance ground resolution (the size of objects a satellite can depict from orbit) to around 50 centimeters. Fretwell says that resolution makes it possible to distinguish individual penguins separated from the group as well as small clusters of birds.
The researchers released a census of Antarctica’s penguins in April 2012 showing a total of 46 separate colonies with a combined population of almost 600,000 birds, nearly twice as many as were previously thought to live in Antarctica. Fretwell says the BAS is working with an international team of researchers and polar explorers including Hubert in Antarctica to adapt the satellite-mapping approach for long-term monitoring of the emperor population. Although the penguins are not endangered, rapidly rising temperatures in the region could wear away the ice that the one-meter-tall birds call home.
The researchers will need to collect three to four more years of satellite and ground data in order to develop a methodology robust enough to track emperor penguin numbers on local, regional and continental scales, Fretwell says. “Ground counts corroborate our satellite data and help us improve our methods,” he says. “But because of the extreme conditions in Antarctica, we have ground data from maybe two of the almost 50 colonies. So there is definitely a lot of work left to be done.”
Hubert, who is not affiliated with the BAS, trekked 50 kilometers from where he was working with Elisabeth Antarctica station glaciologists to visit the bird colony. He says he plans on sharing his observations with the survey when he returns to Europe.
Trathan says satellite mapping could help scientists recognize when populations of isolated emperors and even other species are afflicted by climate change. “If we want to conserve these valuable ecosystems, we need a way to recognize when they are being affected,” he says. “We think emperor penguins are like a canary in a coal mine for climate change. This approach could help us notice when something is wrong before it is too late for any kind of action.”