An emperor penguin with chick. To date, little has been known about exactly where the species breeds and how big the colonies are.
Credit: BAS
A satellite image shows a faint but distinctive stain which gives away the location of an emperor penguin colony.
Credit: BAS
SYDNEY: Penguin poop seen from space has provided the first Antarctic-wide survey of the mysterious breeding colonies of the emperor penguin.
To date, very little has been known about exactly where the penguins (Aptenodytes forsteri) breed, and how big the colonies are. Previous estimates suggested that each colony contains somewhere between 200,000 and 400,000 breeding pairs.
A new study, published today in the journal Global Ecology and Biogeography today, provides the first estimate of the number of colonies and therefore the size of the population. Knowing the location of these colonies is vital for scientists studying the effects of climate change on the species.
Home on the ice
"Until we know its population and distribution it is impossible to accurately assess the extent to which this charismatic species will be endangered," said lead researcher Peter Fretwell, a mapping expert with the British Antarctic Survey (BAS) in Cambridge, England.
Emperor penguins are the largest penguin species, and the only one which breeds during Antarctica's long, dark winter. A single egg is laid by the female and then incubated by the male, who carries it on his feet, insulating it with thick folds of belly flab.
Emperor penguins breed in colonies on sheets of costal sea ice formed during freezing -50°C winter temperatures. Harsh conditions make it too dangerous and expensive to search for these colonies by ship or plane. In spring the ice breaks up, the penguins disperse into the sea, and all trace of the colonies melts away.
Guano marks the spot
Fretwell's team hit upon the idea of using satellite images to identify penguin colonies. He analysed images covering over 90% of Antarctica's coast, collected as part of the Landsat Image Mosaic of Antarctica (LIMA), a project which is part of the International Polar Year.
Although the resolution was not high enough to be able to see individual penguins, large dark orange stains made by penguin droppings, or guano, were clearly visible. Working with study co-author Philip Trathan, Fretwell counted patches representing 38 colonies.
Of these, 10 were colonies that have never been recorded before, said Fretwell. Worryingly, though, six documented colonies could not be found. All the missing colonies were from relatively northern (and therefore warmer) latitudes, suggesting that early melting of coastal ices due to climate change could be responsible.
