An international team of scientists has used satellite images to estimate the number of penguins at each colony around the coastline of Antarctica in order to produce more accurate population studies.
Using a technique known as pan-sharpening, the science teams were able to differentiate between birds, ice, shadow and guano. The pan-sharpening technique involved the merging of a higher-resolution panchromatic image and a lower-resolution color image to produce a single high-resolution color image.
The area covered by penguins was converted into absolute population numbers using a relationship derived from data from colonies where both satellite data and direct ground or aerial counts were available.
"We are delighted to be able to locate and identify such a large number of emperor penguins. We counted 595,000 birds, which is almost double the previous estimates of 270,000-350,000 birds. This is the first comprehensive census of a species taken from space,” says Peter Fretwell from the British Antarctic Survey (BAS).
On the ice, emperor penguins with their black and white plumage stand out against the snow and colonies are clearly visible on satellite imagery. This allowed the team to analyze 44 emperor penguin colonies around the coast of Antarctica, with seven previously unknown.
"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,” said British Antarctic Survey biologist Dr. Phil Trathan.
The research is a collaboration between the British Antarctic Survey, University of Minnesota/National Science Foundation, Scripps Institution of Oceanography and the Australian Antarctic Division.
-- by Dave Wilson, Senior Editor, Vision Systems Design
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