UPDATE: Professor Olaf Eisen, glaciologist at the German Alfred Wegener Institute (AWI), provided us with exciting background information on the emperor penguin colony in Atka Bay. He told Polar Journal in a phone call that the ice thickness of the Ekström ice shelf is decreasing rapidly due to quite strong basal melting. The height of the ice shelf edge above the sea ice, the so-called freeboard, has therefore become very low in recent years and also because no iceberg has calved at this location for a long time. In this way, the ice shelf is losing two to three meters in thickness every year and the edge of the ice shelf is getting lower and lower.
“That’s why last year, when we had a lot more snow than in previous years, a kind of ramp was created at this point, a very shallow ramp from the sea ice onto the shelf. And then it’s no problem at all for the penguins to go onto the shelf,” explains Olaf Eisen. “And depending on when they start to establish their colony, they are then on the shelf. It doesn’t make a big difference to them whether they are up or down, when everything is white and flat anyway.”
The ice shelf will probably no longer be so easy for the penguins to reach when an iceberg breaks off on the eastern side of the Ekström ice shelf at some point and the edge becomes higher again at this location.
However, the majority of the colony, which according to Olaf Eisen comprised around 15,000 pairs this year, bred on the sea ice as usual. Only a small sub-colony chose to breed on the ice shelf. The colony always breeds in the southwestern area of Atka Bay, where various rift systems – cracks in the shelf – have created a hilly landscape where it is easy to get from the ice shelf to the sea ice and back up again.
There are often low clouds in the northern sky that appear very dark when the water is open, he continues. If the chicks use these as a guide on their way towards the ocean, “then some end up at the end of the Ekströmisen [Norwegian for Ekström ice shelf, editor’s note] and others on the sea ice. And at the edge – they’ve never been there before – to draw the conclusion: ‘We’ll go back five kilometers and take the turn’, they just don’t do that.”
Jumping into the water from this height doesn’t bother the chicks much because they are well cushioned by their fluffy baby feathers and their bones are still soft. “On the ice, they occasionally tumble down the mountains. They are genetically prepared for this.”
In 2022, Olaf Eisen was involved in the long-term project “Monitor the health of the Antarctic marine ecosystems using the Emperor penguin as a sentinel” (MARE), which was led by Céline Le Bohec from the French Centre national de la recherche scientifique (CNRS) and in which the University of Erlangen was also involved. Among other things, the research team examined the stomach contents of chicks for microplastics.
Documentary filmmaker Bertie Gregory was the first to capture the bold leaps of Emperor penguin chicks from high ice cliffs in unique drone footage for National Geographic.
Anyone who has ever stood on the 10-meter board in a swimming pool can imagine how emperor penguin chicks must feel on a 15-meter-high ice shelf edge that they have to overcome. Emperor penguins normally breed on fast ice – sea ice that is connected to the ice shelf – and from there a jump into the water is no more than a small hop for the chicks.
But what documentary filmmaker Bertie Gregory observed and filmed with a drone for National Geographic in Atka Bay near the German Neumayer Station at the beginning of January during his shoot for the new documentary Secrets of the Penguins is hard to believe. Around 700 penguin chicks, still wearing the last of their baby fluff over their new adult plumage, march along the edge of the ice shelf, stop at one point and stare indecisively into the depths. They have to jump if they want to learn how to swim and find food. But who will be the first to take the plunge?
“Honestly, I was in awe and I couldn’t believe [National Geographic, editor’s note] caught this footage. Incredible. I would have guessed the chicks didn’t have any other choice but to jump but I’m amazed they were able to record it, since taking that big of a leap would reasonably take a lot of deliberation,” Michelle LaRue, associate professor at the University of Canterbury in New Zealand, tells us in an email.
This is not the first time that emperor penguin chicks have jumped off a high ice cliff, but it is the first time that this unusual behavior has been filmed. More than 30 years ago, Gerald Kooyman, professor emeritus of biology and physiologist at the Scripps Institution of Oceanagrophy in San Diego, who studied emperor penguins in the Antarctic for more than 50 years, observed a similar event, as he describes in his book Journeys with Emperors.
In the recent past, satellite images of this ice shelf edge have occasionally revealed tracks of penguins heading north, Peter Fretwell, a scientist at the British Antarctic Survey, told National Geographic.
But how did the chicks end up on this high ice shelf in the first place? When the parents of the chicks returned to the colony at the beginning of the breeding season, they apparently used a shallow spot along the ice shelf edge to get onto the ice shelf. This route was apparently not an option for the five to six-month-old chicks.
Michelle LaRue explains it to Polar Journal: “I think what happened is that these chicks set off to the north from their colony, which was located up on the ice shelf, not on the sea ice. This ice cliff, I suspect, is directly north of where they were… and I think the chicks simply got perhaps more than they bargained for when they got to the edge [of the ice shelf, editor’s note]. But, remember this is the first time they had ever seen the ocean so it’s not like they had an expectation of what jumping into the water is ‘supposed’ to be like, the way adult emperor penguins might ‘know better’.”
When asked if this unusual behavior of the chicks is related to the sea ice cover, she tells us: “No, I don’t think it would have anything to do with the sea ice. The chicks in this case (if it is true that they were born and raised on the ice shelf and not on sea ice) were probably completely unaware of the existence of sea ice, honestly. […] If it is true that there was less ice in the area when they fledged… in this very specific case anyway… that probably worked to their advantage since it meant they could jump from the cliff into the ocean instead of landing on ice. If there was ice below the cliff I can’t imagine that would have ended well for the chicks. They would have had two options: find another way to the ocean, which would have taken quite a while to figure out, if they were able to figure it out; or jump and land on ice. Neither of those scenarios would be good.”
Peter Fretwell fears that more and more emperor penguins could be forced to breed on the ice shelf in the future as the sea ice recedes. “It really depends on us,” he told Polar Journal in an earlier interview about emperor penguins, referring to our will to reduce greenhouse gas emissions.
Julia Hager, Polar Journal AG
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