The latest very high resolution satellite images have revealed that there are twice as many emperor penguins in Antarctica than previously thought.
The new figures are likely to be a vital benchmark for scientists trying to assess how future changes to the Antarctic climate will affect the birds. Peter Fretwell from the British Antarctic Survey (BAS) is lead author of the study. He said:
We wanted to estimate the Antarctic’s emperor penguin population using a quick-and-easy repeatable survey.
These hardy birds breed in notoriously remote and inaccessible areas of Antarctica, where temperatures can be as low as minus 50°C, which makes using satellite images more efficient, more accurate and cheaper than sending scientists to Antarctica to count them on the ground.
Fretwell and colleagues from BAS, the US and Australia painstakingly analysed medium resolution and very high resolution satellite images of the entire coastline of the white continent in an effort to spot colonies. Once they’d figured out where colonies were, they then used a technique called pan-sharpening to help them distinguish between birds, ice, shadow and penguin poo.
In the process, the researchers discovered four completely new colonies, mostly in West Antarctica, which is particularly difficult to access, said Fretwell. They also confirmed the precise locations of three colonies in East Antarctica, for which, until now, there had been no concrete proof. Fretwell explained:
Explorers had been to areas of East Antarctica and seen emperor penguins, but they hadn’t managed to locate any colonies. But these birds travel around 50 kilometres to reach the sea, so it’s not easy to actually locate colonies.
In total, they identified 46 emperor penguin colonies. Actual counts of penguins in a handful of sites on the ground then let the team calculate that the 46 colonies are made up of around 595,000 adults.
The team describeed their results in PLoS One.
This is the first time scientists have worked out the size of an animal’s entire population from space.
Many scientists are concerned that earlier spring temperatures in some regions of Antarctica and the resulting loss of sea ice will spell certain trouble for emperor penguins.
Recent research has revealed that they’re highly susceptible to changes in sea-ice cover. Indeed, substantial regional losses of sea ice over the last few decades resulting from climate change have been blamed for the loss of one emperor penguin colony from the Antarctic Peninsula. This region of the continent has warmed faster than any other.
Some scientists predict that sea ice will shrink by around a third in the second half of this century. Others suggest that penguins will no longer be able to live north of 70 degrees south. Fretwell said
Our method now enables us to monitor Antarctica’s emperor penguin population to test the accuracy of these predictions and models.
Dr. Phil Trathan, also from the British Antarctic Survey, is co-author of the paper. He said:
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.
Bottom line: Good news for penguin lovers! The latest very high resolution satellite images have revealed that there are twice as many emperor penguins in Antarctica than previously thought.
Planet Earth online is the companion website to the award-winning magazine Planet Earth published and funded by the Natural Environment Research Council (NERC).