Satellite image courtesy University of Minnesota
Emperor penguins in Erebus Bay. Photograph courtesy Michelle LaRue, University of Minnesota.
Published April 13, 2012
Talk about a bird's-eye view—scientists have taken the first-ever penguin census from space.
What's more, the high-resolution satellite images reveal that there are twice as many emperor penguins in Antarctica than previously thought, a new study says.
Scientists have snapped penguin pictures from space before. But the new work used a technique called pansharpening, which offers high enough resolution for the scientists to differentiate between penguin poop, ice, and the birds themselves.
It's the same thing as "when you're looking through binoculars and tightening them up, making [your subject appear in] finer detail," said study co-author Michelle LaRue, a Ph.D. student in conservation biology at the University of Minnesota.
When LaRue first looked at the sharper satellite images, "I didn't believe that they were actually penguins," she said.
But when "you see it again and again ... there's nothing else it could be."
Emperor Penguins Easy to Spot
The penguin-counting team examined images taken in 2009 by the privately owned Quickbird2, Worldview2, and Ikonos satellites.
From these pictures, the scientists counted about 595,000 emperor penguins—almost double the previous estimates of 270,000 to 350,000 animals made in 1992.
Found only in Antarctica, the 4-foot-tall (1.2-meter-tall) flightless birds are hard to study because they live in almost inaccessible, frigid colonies.
But their group living, coupled with distinct black-and-white plumage, makes the penguins easy to spot from the air, according to study leader Peter Fretwell of the British Antarctic Survey.
The team also identified 7 new emperor penguin colonies, bringing the total to 44, Fretwell said. (Watch video: "Penguins Do the Wave to Keep Warm.")
"We are delighted to be able to locate and identify such a large number of emperor penguins," Fretwell said in a statement.
(Learn how you can see penguins firsthand with National Geographic Expeditions.)
Penguins Not Off the Hook
The higher emperor penguin count is "welcome news," penguin expert P. Dee Boersma, of the University of Washington in Seattle, said in an email.
"The use of new technology like satellite mapping allows scientists to determine locations and numbers of emperor penguins in a way previously impossible," she said.
However, although the technology "is a leap forward, ... it doesn't change the conservation concern for emperor penguins and many other species."
The emperor penguin is currently classified as a species of least concern by the International Union for Conservation of Nature, said study co-author LaRue.
But scientists are concerned about emperor populations in northern Antarctica, where warmer spring temperatures are melting the sea ice on which the birds depend. Southern emperor penguin colonies, meanwhile, will likely not be affected by global warming, because the sea ice there is predicted to remain stable.
With the new satellite-based strategy, "we can start monitoring [the penguins] through time," said LaRue, whose study appears this week in the journal PLoS ONE.
For example, "if we saw a population crash in one location, we could see if it's unique to that location" and whether the crash is related to climate change. The higher-resolution satellite pictures will give scientists "baseline information to be able to start answering those different questions."
"The methods we used," she said, "are an enormous step forward in Antarctic ecology."
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