Caroline Morley, online picture researcher
Counting emperor penguins (Aptenodytes forsteri) cannot be easy. They spend much of their time in the Antarctic Ocean and when they do come on land it's for winter in some of the remotest, coldest and windiest places on Earth.
Fortunately, a team from the British Antarctic Survey (BAS), University of Minnesota, Scripps Institution of Oceanography and the Australian Antarctic Division have found an easier way to keep tabs on the penguins - satellite images.
Using images of the colonies like this one, the team counted a total of 595,000 birds, much higher than previous estimates of 270,000 to 350,000. The satellite images also helped the researchers to find seven previously unknown colonies, taking the total to 44.
Peter Fretwell from BAS said: "This is the first comprehensive census of a species taken from space."
(Image: British Antarctic Survey)
Previously the team had used satellite images to identify the location of penguin colonies by large brown smears of guano on the ice. The new census took their view closer by using a technique called pan-sharpening to increase the image resolution so they could pick out the birds from their shadows as well as the guano. The results from the satellite images, taken in 2009, were also calibrated using ground counts and aerial photography.
As an animal that relies on floating sea ice for its breeding and nesting grounds, emperor penguins are thought to be particularly vulnerable to any warming of ocean temperatures from climate change.
BAS biologist and team member Phil Trathan said: "Current research suggests that emperor penguin colonies will be seriously affected by climate change. 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."