Scientific name: Pygoscelis adeliae
Adélie penguins were discovered in 1840 by scientists on the French Antarctic expedition led by explorer Jules Dumont d’Urville. D’Urville named Adélie Land, in southern Antarctica, after his wife, Adéle. Scientists Jacques Hombron and Charles Jacquinot also attributed this name to the species.
Adélie penguins are medium sized penguins, weighing 3 to 6 kg and standing 70 cm tall. They are distinguished by the white ring surrounding the eye. Males and females are of similar size and difficult to tell apart.
Like all penguins, Adélies are excellent swimmers. They are also very determined and successful long distance walkers travelling across many kilometres of fast ice on the return journey to their colonies. Their walking speed on ice averages 2.5 km/h and swimming speed 4 to 8 km/h. When enough snow covers the ice, they prefer to plonk onto their bellies and toboggan.
They are closely related to the gentoo (Pygoscelis papua) and the chinstrap (Pygoscelis antarctica) penguins.
Distribution and abundance
Adélie penguins breed around the entire Antarctic coast and small islands in places where there is exposed rock. Many of these locations are close to the Australian research stations.
Long-term population research focuses on the Windmill Islands near Casey, home to the third largest Adélie population in East Antarctica. Scientists have shown the colonies here have increased from 30,000 breeding pairs in the 1950s to nearly 200,000 today. A small colony of about 1,800 breeding pairs are studied on Béchervaise Island near Mawson, as part of a long term ecosystem monitoring program.
Scientists know much more about the behaviour of Adélies in the warmer months, because they breed on land between October and February. Less is known about their behaviour in the winter where they spend time at sea in the pack ice. Scientists are tracking their routes so they can find out exactly where the Adélies go on their long sea journeys. So far, scientists know that these penguins can swim more than 1,200 km away from their breeding site.
Conservation status: least concern
In spring, Adélie penguins build nests out of the pebbles they find on dry land. They choose a sloping site so that, when the snow melts, water runs away from the nest. When the pack ice has not yet broken up, finding food nearby can be a problem. Adélies may have to walk over 50 km across the ice to reach the sea. Individuals always return to the same nest and the same mate, if they can.
By mid-November there are 2 eggs in the nest. Parents take turns to incubate the eggs and find food. The first two incubation shifts tend to last 11 to 14 days and are followed by shorter shifts. The chicks hatch in December and the parents alternate guard and feeding duties swapping every few days. The adults catch fish, krill and other small crustaceans, which they regurgitate for their chicks. The chicks on Béchervaise Island put on around 80 grams per day.
In January, when chicks are 3 weeks old, they are big enough to be left alone. This allows both parents to simultaneously collect food for them. When the parents are away the chicks group together for protection and warmth.
In February, the chicks replace their down with adult feathers. At the age of 7 to 9 weeks they are ready to go to sea. Most chicks will not return to the breeding colony until they are 3 to 5 years of age and capable of breeding. Adélie penguins have a life expectancy of 10 to 20 years.
Diet and feeding
The diet of Adélies differs according to the location where food is captured. Local meals (those within 20 km of the colony) consist mostly of fish, amphipods and ‘crystal krill’ (Euphausia crystallorophias), while offshore meals consist of mainly ‘Antarctic krill’ (Euphausia superba). Meal sizes range from about 300 to 650 g depending on the size of the chicks.
Breeding adults swim between 5 to 120 km offshore to catch food for their chicks. Feeding trips range from 5 to 72 hours in duration.
Some Adélie penguins are capable of diving to depths of up to 175 m but usually feed within the upper 70 m of the water column.
Adélie satellite tracking
Scientists have attached satellite transmitters to selected Adélies so they can track their movements when out at sea feeding. The transmitters send signals to an orbiting satellite which relays the signals to the Australian Antarctic Division at Kingston, Tasmania. The sea routes of the penguins can then be mapped. Scientists often use dive depth recorders as well to determine how deep the penguins dive to catch their prey.
Automated Penguin Monitoring System
Australian scientists have revolutionised the gathering of data from penguins. Before the new method was in place, scientists had to handle penguins repeatedly to obtain the data required. Now, the Automated Penguin Monitoring System is used to automatically weigh, identify and determine the direction of penguins as they walk across a weighing platform placed between the breeding colony and the sea. This method of gathering data ensures the least disturbance and is less stressful for the penguins.
To identify each bird, scientists use a tiny electronic tag which they implant under the skin of the penguins. As the birds step onto the platform, their tag activates the system. Readings can then be obtained of how long each bird has been away foraging and how much food the bird gives to its chick. The weighing of penguins is important, as scientists can then tell how much krill and fish they are eating and delivering to their chicks.