In a new study, scientists from the British Antarctic Survey (BAS) used satellite images to survey Antarctica’s coast to search for emperor penguin colonies as it turns out penguin guano stains are visible from space.
There was little known about the number and distribution of emperor penguin colonies because researches can only visit the area during the Antarctic summer and the penguins are away feeding at sea and only breeding on sea-ice during the Antarctic winter. The reddish brown patches of guano on the ice, that are visible in the satellite images, provide a reliable indication of their location.
The BAS scientists surveyed the sea-ice around 90% of Antarctica’s coast identifying a total of 38 existing colonies. Ten of those were new. Of the previously known colonies six had re-located and six were not found. Estimates of the total number of emperor penguins range between 200,000 – 400,000 pairs.
Emperor penguins are the tallest and heaviest of all penguin species and spend a large part of their lives at sea. During the Antarctic winter when temperatures drop to −50°C (-58F) they return to their colonies to breed on sea-ice, but this is a time when it is most difficult for scientists to monitor them.
“We can’t see actual penguins on the satellite maps because the resolution isn’t good enough. But during the breeding season the birds stay at a colony for eight months. The ice gets pretty dirty and it’s the guano stains that we can see” said Peter Fretwell, a BAS mapping expert and author of the survey.
BAS Penguin ecologist and co-author of the survey Dr. Phil Trathan says: “This is a very exciting development. Now we know exactly where the penguins are, the next step will be to count each colony so we can get a much better picture of population size. Using satellite images combined with counts of penguin numbers puts us in a much better position to monitor future population changes over time.”
Knowing their location provides a baseline for monitoring their response to environmental change. French scientists extensively studied one colony and found the population was at significant risk from climate change. The six colonies not found in this study were at a similar latitude suggesting that emperor penguins may be at risk all around Antarctica.
The Emperor Penguin is listed as a species of “least concern” by the IUCN. Along with nine other species of penguin, it is currently under consideration for inclusion under the US Endangered Species Act.
This study concentrates on the number and location of emperor penguin colonies; other techniques are necessary to provide accurate counts within these colonies. The next stage of this research will be to use high resolution satellite data to count up the penguins at each of the 38 colonies.
A Woods Hole Oceanographic Institution study in January 2009 found emperor penguins could be pushed to the brink of extinction by the year 2100 due to global climate change. By applying mathematical models to predict how the loss of sea ice from climate warming would affect a big colony of emperor penguins at Terre Adélie, Antarctica, they forecast a decline of 87% in the colony’s population by the end of the century. The new methods developed in the study by Fretwell and Trathan make it possible to test these predictions at other locations where emperor penguins breed, particularly further South where the majority of emperor penguin colonies occur.
This new study “Faecal stains reveal the location of emperor penguin colonies” was published this week in the journal Global Ecology and Biogeography.
Copyright © 2009 by Marine Science Today, a publication of OceanLines LLC