NGS photo of Emperor penguins by W. Edward Roscher
Emperor penguin colony at Halley Research Station
Photo courtesy British Antarctic Survey
Penguin poop (guano) stains, visible from space, have helped British scientists locate emperor penguin breeding colonies in Antarctica, the British Antarctic Survey (BAS) said today.
Knowing the location of the penguins provides a baseline for monitoring their response to environmental change.
In a study published this week in the journal Global Ecology and Biogeography, BAS scientists describe how they used satellite images to survey the sea ice around 90 percent of Antarctica’s coast to search for emperor penguin colonies.
Ten New Emperor Penguin Colonies Found
“The survey identified a total of 38. Ten of those were new. Of the previously known colonies six had re-located and six were not found,” BAS said.
“Because emperor penguins breed on sea-ice during the Antarctic winter little is known about their colonies. Reddish brown patches of guano on the ice, visible in satellite images, provide a reliable indication of their location.”
“We can’t see actual penguins on the satellite maps because the resolution isn’t good enough,”
BAS Mapping expert Peter Fretwell explains in a BAS news release. “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.”
Satellite image showing guano stains of an emperor penguin colony in Halley Bay, Antarctica
Image courtesy British Antarctic Survey
Emperor penguins spend a large part of their lives at sea. During the Antarctic winter when temperatures drop to minus 58 degrees Fahrenheit (minus 50 degrees Celsius). 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.
“Now we know exactly where the penguins are.”
– BAS Penguin Ecologist Phil Trathan
“This is a very exciting development,” BAS Penguin Ecologist Phil Trathan says. “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.”
This research builds on work by French scientists who 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, BAS said.
Landsat Image Mosaic of Antarcitca (LIMA) image courtesy USGS
How It Was Done
From the abstract of the research paper in Global Ecology and Biogeography:
“Using Landsat ETM satellite images downloaded from the Landsat Image Mosaic of Antarctica (LIMA), we detect fecal staining of ice by emperor penguins associated with their colony locations.
“Emperor penguins breed on sea ice, and their colonies exist in situ between May and December each year.
“Fecal staining at these colony locations shows on Landsat imagery as brown patches, the only staining of this colour on sea ice. This staining can therefore be used as an analogue for colony locations.
“The whole continental coastline has been analyzed, and each possible signal has been identified visually and checked by spectral analysis. In areas where LIMA data are unsuitable, freely available Landsat imagery has been supplemented.”
Results: “We have identified colony locations of emperor penguins at a total of 38 sites. Of these, 10 are new locations, and six previously known colony locations have been repositioned (by over 10 km) due to poor geographical information in old records. Six colony locations, all from old or unconfirmed records, were not found or have disappeared.”
Map of locations of Emperor penguin colonies in Antarctica courtesy British Antarctic Survey
Main conclusions: ”We present a new pan-Antarctic species distribution of emperor penguins mapped from space. In one synoptic survey we locate extant emperor penguin colonies, a species previously poorly mapped due to its unique breeding habits, and provide a vital geographical resource for future studies of an iconic species believed to be vulnerable to future climate change.”
Why are emperor penguin population numbers important?
From the British Antarctic Survey Web site
Emperor penguins on the sea ice close to Halley Research Station on the Brunt Ice Shelf. The young Emperor chicks are moulting.
Emperor penguins (Aptenodytes forsteri) breed in colonies on the sea ice that surrounds much of the coast of Antarctica.
These colonies can range in size from a few hundred to many thousands of pairs, however, scientists have been unable to estimate the total number of emperor penguins in Antarctica.
The colonies generally only exist in the most inaccessible of locations and access during the harshest weather conditions is extremely difficult.
In addition, we don’t know where all the colonies are located.
Estimates of the total number of penguins range between 200,000 and 400,000 pairs, but changes in the sea ice on which they breed can affect their breeding success and the size of the colony.
We therefore need a more accurate assessment of their numbers to help us monitor future penguin population changes, and in particular, their response to climate change.
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