Adélie penguin research
My name’s Colin Southwell. I work at the Australian Antarctic Division, and I’m a seabird ecologist.
In our paper we aimed to assess change in Adélie penguin populations across East Antarctica over the last 30 years. We worked with colleagues from France and Japan to try and cover the full extent of East Antarctica. Now that’s a really large area. It’s a coastline of around about 5000 km, there are over 200 colonies in that area. And what we did was look back at what historical data there was for populations back in the early 1980s and we tried to go back to those same sites and do counts in the 2000s, so that we could compare if the populations had changed over that time.
What we found is that in five regional populations spread right across East Antarctica there’d been a consistent increase of around about the same rate and extent in the populations since 1980. So over 30 years, overall the populations had increased by 70 per cent.
Within the region there was some variability. So within the Davis area for instance, as an example, most of the populations increased at different colonies, but some decreased. And this was happening across all of the regions. So what that told us was that there were some local effects driving populations, but overall there must have been some kind of regional driver of that population change.
There is evidence there’s been quite a substantial decrease in sea ice across East Antarctica in the mid-20th century. It’s possible that the reducing sea ice could have made prey more available to the Adélie penguins. The other thing that happened back in the 20th century was that there was extensive fishing for fish, krill, and also harvesting of whales, and in the 1970s there was a hypothesis called the krill surplus hypothesis that proposed that that would have made available many more krill to other predator populations such as Adélie penguins.
Our work has answered some questions but posed many others. So we worked on Adélie penguins because they’re convenient to study. They’re one of the few components of the marine ecosystem that we can work with easily. But we only have knowledge on a few pieces in this big ecosystem puzzle. And if we can get more information on other parts of the puzzle, other species, particularly the marine species that don’t come on to land to breed then we’re going to be able to piece together the mechanisms of ecosystem change much better than we can. So of course there’s more work that we could do, if only we could measure the marine environment better. Now one way we might be able to do that is to have new technologies that could make those measurements for us, and work on new technologies for making observations, I think, is very important.
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 3–6 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 4–8 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. More than 80 000 pairs of Adélie penguins breed annually along the 40 km of Antarctic coast near Mawson station. Scientists at the Australian Antarctic Division study the Adélie penguin colony on Béchervaise Island, near Mawson as part of a long term ecosystem monitoring program. This colony is one of the smaller Adélie colonies consisting of around 1 800 breeding pairs.
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 two eggs in the nest. Parents take turns to incubate the eggs and find food. The first two incubation shifts tend to last 11–14 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 ~80 grams per day.
In January, when chicks are three 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 7–9 weeks they are ready to go to sea. Most chicks will not return to the breeding colony until they are 3–5 years of age and capable of breeding. Adélie penguins have a life expectancy of 10–20 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 300–650 g depending on the size of the chicks.
Breeding adults swim between 5–120 km offshore to catch food for their chicks. Feeding trips range from 5–72 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.