Scientists almost doubled estimated emperor penguin numbers by using satellite imagery powerful enough to distinguish the birds from their poop stains and shadows on the ice, findings that may help track climate change.
It was the first comprehensive survey of a species from space, said Peter Fretwell, lead author of a paper published Friday in the PLoS One journal. Researchers led by the British Antarctic Survey found about 238,000 breeding pairs in the southern continent, according to the report. That compares with a two-decade-old estimate of 135,000 to 175,000 pairs.
“Current research suggests that emperor penguin colonies will be seriously affected by climate change,” Phil Trathan, a co-author of the paper, said in an e-mailed statement. “An accurate continent-wide census that can be easily repeated on a regular basis will help us monitor more accurately the impacts of future change on this iconic species.”
The Antarctic Peninsula, the portion of the continent that points toward South America, has warmed by 2.5 degrees Celsius (4.5 degrees Fahrenheit) in the past 50 years, according to the European Space Agency. That led to the collapse of the Larsen B ice shelf and loss of part of the Wilkins ice shelf, threatening the habitat of penguins, which tend to live in coastal areas.
“While current research leads us to expect important declines in the number of emperor penguins over the next century, the effects of warming around Antarctica are regional and uneven,” Trathan said. “In the future we anticipate that the more southerly colonies should remain, making these important sites for further research and protection.”
The team used Very High Resolution satellite images able to distinguish between birds, shadows on the snow and ice, and their excrement, or guano, to measure populations of 46 colonies. The researchers estimated that when non-breeding birds are included from outside colonies, the adult penguin population was about 595,000 birds.
The British Antarctic Survey had previously used “reddish brown patches” of guano left on the ice by penguins to identify the colonies, it said in a statement on its Web site from 2009.
Researchers included scientists from the University of Minnesota in Minneapolis, the Scripps Institution of Oceanography at the University of California in San Diego, and the Australian Antarctic Division in Hobart, Tasmania.
The emperor penguin, which inhabits only Antarctica, is of “least concern” on the Red List of endangered species compiled by the International Union for Conservation of Nature.
“March of the Penguins,” a French nature documentary about the species by Luc Jacquet and narrated by actor Morgan Freeman, won an Academy Award in 2005 for best documentary feature.