ScienceDaily (Apr. 13, 2012)
— A new study using satellite mapping technology reveals there are
twice as many emperor penguins in Antarctica than previously thought.
The results provide an important benchmark for monitoring the impact of
environmental change on the population of this iconic bird, which breeds
in remote areas that are very difficult to study because they often are
inaccessible with temperatures as low as -58 degrees Fahrenheit.
Using a technique known as pan-sharpening to increase the resolution of the satellite imagery, the science teams were able to differentiate between birds, ice, shadow and penguin poo or guano. They then used ground counts and aerial photography to calibrate the analysis.
Lead author and geographer Peter Fretwell at British Antarctic Survey (BAS), which is funded by the U.K.'s Natural Environment Research Council, explains, "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."
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, and seven previously unknown colonies.
"The methods we used are an enormous step forward in Antarctic ecology because we can conduct research safely and efficiently with little environmental impact, and determine estimates of an entire penguin population, said co-author Michelle LaRue from the University of Minnesota and funded by the U.S. National Science Foundation (NSF).
"The implications of this study are far-reaching: we now have a cost-effective way to apply our methods to other poorly-understood species in the Antarctic, to strengthen on-going field research, and to provide accurate information for international conservation efforts."
NSF manages the U.S. Antarctic Program through which it coordinates all U.S. scientific research on the southernmost continent and aboard ships in the Southern Ocean as well as related logistics support.
Co-author and BAS biologist Phil Trathan noted, "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."
Scientists are concerned that in some regions of Antarctica, earlier spring warming is leading to loss of sea ice habitat for emperor penguins, making their northerly colonies more vulnerable to further climate change.
Trathan continued, "Whilst 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. In the future, we anticipate that the more southerly colonies should remain, making these important sites for further research and protection."
This research is a collaboration between BAS, University of Minnesota/NSF, Scripps Institution of Oceanography and the Australian Antarctic Division.
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Journal Reference:
- Peter T. Fretwell, Michelle A. LaRue, Paul Morin, Gerald L. Kooyman, Barbara Wienecke, Norman Ratcliffe, Adrian J. Fox, Andrew H. Fleming, Claire Porter, Phil N. Trathan. An Emperor Penguin Population Estimate: The First Global, Synoptic Survey of a Species from Space. PLoS ONE, 2012; 7 (4): e33751 DOI: 10.1371/journal.pone.0033751
1 comment:
Interestingly one of the authors, B. Wienecke also has a paper in Polar Biology online first of 20 March 2012.
This is about two colonies found on the West Ice Shelf in 2009-2011.
These are not found on the satellite survey of 2009 so presumably, like the Peterson Bank and Ledda Bay colonies did not nest that year.
This suggests that 5-7 percent of colonies may fail each year and you may need four or five years of consecutive satellite surveys to pick up all colonies.
LeeB.
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