Nothing is as strongly associated with the icy habitats of Antarctica like the Emperor penguin (Aptenodytes forsteri). These well-loved tuxedoed birds rose to international fame with the movie Happy Feet in 2006, a movie which, behind the singing and dancing penguins, highlighted the environmental plight of these birds due to commercial fisheries placing strain on fish resources in the Southern Ocean.
Perfectly Adapted Birds
Emperor penguins are one of the few animals that breed during the harsh Antarctic winters, to allow their chicks to fledge in late spring and early summer. They have several layers of scale-like feathers and a vast fat reserve that protects them against winter winds up to 60 knots (110 kilometers per hour). They also have small beaks and flippers relative to their overall body size to prevent heat escaping their bodies. Thanks to their social natures, they have adapted to huddle together during winter to keep warm in the minus 58 degrees Fahrenheit temperatures.
This penguin species breeds in large colonies scattered across the Antarctic continent. The colonies can range from a few hundred to over twenty thousand pairs of penguins. These colonies are mostly situated on fast-ice – ice fields that are locked between islands or grounded icebergs close to the Antarctic coast line.
Penguins From Space?
Is it possible to see Emperor penguin colonies from space? Scientists from the British Antarctic Survey (BAS) have used satellite imagery to survey sea-ice and ice fields along Antarctica’s coast in search of new Emperor penguin colonies. Since these penguins breed on sea-ice during winter, little is known about their colonies due to inaccessibility. Although researchers can access these sites during the summer months, Emperor penguins spend months feeding at sea during summer, therefore researchers cannot count their population sizes. The survey undertaken by BAS identified a total of 38 colonies (which forms part of the global census of 61 colonies around the Antarctic continent), eleven of which were never before seen. Of the previously known colonies, six had relocated, and six were never found. This new study determined that there are nearly 20% more Emperor penguin colonies in Antarctica than was previously thought. However, due to the small size of the eleven new colonies, it only increases the overall Emperor penguin population size by five to ten percent, to an estimated total of 557 000 penguins.
The European Space Agency’s Copernicus Sentinel-2 satellite was used to obtain imagery of penguin colonies. This satellite was launched in June 2015, and has a resolution of 10 meters, enabling it to observe smaller colonies. The satellite imagery used to locate these colonies did not spot the penguins themselves, but instead the researchers use the imagery to locate the reddish-brown patches of guano – i.e. penguin poop – to locate the colonies. Due to the resolution of the satellite images, the penguins cannot be seen on the pictures. However, since colonies stay stationary for up to eight months during breeding season, the ice gets fairly dirty, and it is these stains that can be observed from space.
Two of the newly observed colonies were a surprise to researchers, as they were found far from the coast, living on sea ice anchored to a grounded iceberg, a location never seen before. One colony was found 112 miles from the Antarctic continent, which is unusual as normally the colonies are found on stable sea ice closer to the coast. These new colonies are thought to be smaller than average, containing only a few hundred penguins each.
Once the locations of the penguin colonies are determined, researchers can conduct accurate penguin counts at each colony, which will result in a better picture of the overall population size of the species. This will allow researchers to better monitor changes in population sizes over time. The next step is to direct satellites with extremely high, 30 cm-resolution cameras to the colonies to allow scientists to count the population without having to traverse the sea ice.
Emperor Penguins Threatened By Climate Change
Emperor penguins are the only penguins to breed on sea ice, rather than land, making them vulnerable to climate change. As global temperatures continue to increase, sea ice is melting, and researchers say these penguin colonies will be the “canaries in the coal mine”, acting as indicators as Antarctica is increasingly affected by global warming. With current climate predictions, the breeding habitat of Emperor penguins is likely to decline. With the newly found colonies located on the margins of the Emperor penguin’s breeding range, it is possible that these locations will soon be lost as the climate continues to warm.
Future of the Emperor Penguins
Although dynamics between Emperor penguin colonies will differ, it is estimated that all colonies will decline in size by the end of the century. A study published in the Nature Climate Change Journal has suggested that 80% of Emperor penguin colonies will decrease by more than 90% by the end of the century if the sea ice around Antarctica decreases to half its current size and extent. Even with the best-case scenario of a global temperature increase of 1.5oC, the Emperor penguin population will decrease by at least 31% over the next three generations. Despite these ongoing threats, the Emperor penguin is only listed as Near Threatened on the IUCN Red List of Threatened Species.
Not The First Time
This is not the first time that satellite imagery has been used to locate penguin colonies. In 2018 a study announced the presence of a large, previously unknown colony of Adélie penguins that was spotted on the most northerly point of the Antarctic Peninsula. This colony numbered more than 1.5 million birds, and similar to the Emperor penguins, the colony was first noticed when great patches of guano showed up on satellite images. This colony is located on a rocky archipelago called the Danger Islands, and due to its remote location, no one had previously thought to search there. Unlike the Sentinel-2’s imagery, the imagery used to locate the Adélie penguins was provided by the Landsat spacecraft, which produces low-resolution images. Drones were therefore deployed to the sites, to allow for accurate population counts.