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| Emperor penguins on the sea ice close to Halley Research Station. Photo credit: British Antarctic Survey |
ANTARCTICA – A new study
using satellite mapping technology reveals there are twice as many emperor
penguins in Antarctica than was previously thought.
The results provide an
important benchmark for monitoring the impact of environmental change on the
population of this iconic bird. Emperor penguins breed in areas that are very
difficult to study because they are remote and often inaccessible with
temperatures as low as −50°C (−58°F).
Reporting in the journal
PLoS
ONE, an international
team of scientists describe how they used Very High Resolution satellite images
to estimate the number of penguins at each colony around the coastline of
Antarctica.
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
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 UK’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
analyse 46 emperor penguin colonies around the coast of Antarctica, including
seven that were previously unknown.
“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 US National Science Foundation.
“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 ongoing
field research, and to provide accurate information for international
conservation efforts.”
BAS biologist and
co-author Dr 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.
Dr 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.”
The research is a
collaboration between British Antarctic Survey, University of
Minnesota/National Science Foundation, Scripps Institution of Oceanography and
the Australian Antarctic Division.
PloS ONE citation
An emperor penguin
population estimate: the first global, synoptic survey of a species from space,
Fretwell PT, LaRue MA, Morin P,
Kooyman GL, Wienecke B, et al. (2012). PLoS ONE 7(4): e33751.
doi:10.1371/journal.pone.0033751
Sources
Scientists
count penguins from space, 13 April 2012, British Antarctic Survey
Scientists
determined first-ever census for emperor penguin, 13 April 2012, National
Science Foundation
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