Stains of penguin poop visible from space are helping scientists map emperor penguin colonies, shedding light on how the flightless birds are adapting to environmental changes.
The emperor is the giant of the penguin world and one of the largest of all living birds.
Emperor penguins spend a large part of their lives at sea. But come time to breed, they return to their sea-ice colonies.
This homecoming happens during the Antarctic winter, when temperatures drop to minus 58 degrees Fahrenheit (minus 50 degrees Celsius), a difficult time for scientists to monitor the birds movements. (Emperors are the only penguin species that breed during the winter.)
But all those bird bodies crowded together leave reddish brown patches of guano (penguin poop) on the ice. These patches are visible in satellite images, and so can act as a reliable trace of where the penguins have been.
"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," said Peter Fretwell of the British Antarctic Survey (BAS). "The ice gets pretty dirty and it's the guano stains that we can see."
With the satellite images, the BAS team surveyed the sea-ice around 90 percent of Antarctica’s coast and identified 38 colonies. Ten of those were new. Of the previously known colonies, six had moved and six were not found.
"This is a very exciting development. Now we know exactly where the penguins are, the next step will be to count each colony so we can get a much better picture of population size," said team member Phil Trathan, a penguin ecologist with the BAS. "Using satellite images combined with counts of penguin numbers puts us in a much better position to monitor future population changes over time."
Estimates of the total number of emperor penguins range between 200,000 to 400,000 pairs.
This research, detailed this week in the journal Global Ecology and Biogeography, builds on work by French scientists who extensively studied one colony and found the population was at significant risk from climate change.
The six colonies not found in this study were at a similar latitude suggesting that emperor penguins may be at risk all around Antarctica.
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