A rover quietly surveys the forbidding icy landscape. Suddenly, it whirrs into life: it has spotted an emperor penguin. With its antenna set to scan, the 90-centimetre-long robot trundles towards the bird, searching for a signal from an RFID chip beneath the penguin’s skin – recording crucial information that may help us finally understand this enigmatic species.
The emperor penguin is instantly familiar as the star of countless nature documentaries and the . This media exposure might give the impression that we have a solid understanding of its biology. We don’t. Almost all of that footage was collected from just two breeding colonies on opposite sides of Antarctica, constituting perhaps 10 per cent of the emperor penguin population. For decades, the hundreds of thousands of emperors living elsewhere along the continent’s coast were virtually unstudied.
That situation is now changing. Over the past 15 years, researchers have uncovered more about these birds using new technologies, including satellites that can spot colonies from space and AI-equipped robots to scan them on the ground. “I hope we’re starting to go into a golden age of research,” says at Woods Hole Oceanographic Institution, Massachusetts.
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Already, the work has revealed subtle differences in the genetics and behaviour of the penguins at different points around the Antarctic coast, and shown that they are surprisingly adaptable to changing conditions. But these discoveries have been made amid rapid warming in the region, which led the US Fish and Wildlife Service to declare emperors a . Can new insights help us protect one of the world’s most iconic birds?
Why penguin size matters
At 1.2 metres tall, the emperor is the largest living penguin species. Its size may be an adaptation for life in Antarctica – bigger bodies conserve heat better than smaller ones – but it has knock-on effects for behaviour. For instance, smaller penguins will readily hop or clamber over rough terrain, but emperors struggle to do so. They can only march, slowly, across flat ground. This explains why emperors rarely stray onto land. When they exit the water, they typically do so onto “fast ice” – relatively flat sea ice that is stuck fast to the coast, the side of a glacier or another object.
It is on this fast ice that most emperor penguins breed – and again, their size is a factor in their breeding behaviour. “Smaller penguins can complete their breeding cycle within the short Antarctic summer,” says at the British Antarctic Survey (BAS) in Cambridge, UK. “But when you’re raising a larger chick, you just haven’t got the time.”
Instead, the female emperor penguin lays a single egg in May or June, just before the peak of the Antarctic winter. She passes it to the male, who tends to the egg on the fast ice as temperatures plunge below -50°C (-58°F). The chick hatches towards the end of winter and spends its first months on the ice. It fledges around mid-December – in the Antarctic summer – at which point it has sufficiently waterproof feathers to survive the cold waters.
This unique practice means emperors have to choose their breeding sites carefully. On the one hand, they must avoid places where the fast ice grows and extends too far from the colony during the winter, because then it takes the adults too many days to trudge to the sea for food and the hungry chicks starve. On the other hand, they must also avoid places where the fast ice recedes too rapidly in the Antarctic summer, because the colony risks falling into the sea before the chicks have fledged, meaning most will drown. “It’s a really fine balance,” says Fretwell.
The challenges of conducting research on and around the hostile Antarctic meant that it was once extremely difficult to know how often penguins get that balance right. Then, 15 years ago, Fretwell and his BAS colleague made a pivotal discovery. They realised that known , due in part to the way penguin droppings stain the ice.
Discovering new colonies
By analysing satellite images, Fretwell and Trathan identified 28 known colonies – and an additional 10 that were previously unknown. Since then, improvements in satellite imaging resolution have helped identify even more. As recently as last year, Fretwell spotted , bringing the total number to 66. “It’s incredible what we can do now compared to just a few decades ago,” he says. There are now plans to use synthetic-aperture radar satellites, which create a high-resolution 3D map of the ground and will allow researchers to track the penguins even , when the colonies experience several weeks of total darkness, says Fretwell.
More people have travelled in space than have handled emperor penguins
The satellite images obtained so far have underscored the emperors’ ability to survive against the odds. For example, last year satellites spotted a huge glacier coming to a halt next to a breeding colony at Halley Bay in east Antarctica, apparently trapping the birds on the fast ice there. Somehow, . Perhaps the adults found a way to dive beneath the iceberg to reach the open waters of the Weddell Sea where they forage for food for their chicks.
But satellite observations get you only so far. Even with modern high-resolution images, it is challenging to get accurate penguin population counts. All you can really do is measure the ground area the colony covers and take an educated guess as to how many penguins are packed inside that space. “It’s incredibly uncertain,” says Zitterbart.
On-the-ground observations can boost accuracy, and here researchers rely on the fact that two breeding colonies – at Atka Bay and Pointe Géologie – lie within a few kilometres of scientific stations, making them relatively accessible for researchers. Zitterbart and his colleagues analysed these colonies a few years ago and discovered that they could use temperature and wind-speed data to predict whether the penguins would be scattered across the landscape or . In a study published last year, they argued that this greater understanding of penguin behaviour should allow for using satellite images. Put simply, researchers could use data from weather stations to estimate penguin density at the time a given satellite image of a colony was captured.
However, such research assumes that all 66 breeding colonies are fundamentally similar to those at Atka Bay and Pointe Géologie. It is becoming increasingly clear that this may not be the case. In 2017, , who is now at the University of Tasmania, Australia, and her colleagues collected DNA samples from 110 emperor penguins at eight colonies around Antarctica and found subtle signs that subpopulations that rarely mix. In 2023, another research team led by at Sorbonne University in Paris used satellite images to suggest that each of these subpopulations has developed . For instance, colonies in east Antarctica are found where fast ice remains stable deep into the Antarctic summer, but, surprisingly, those in the Ross Sea tend to occur where the fast ice melts early in the summer. Labrousse and her colleagues concluded that the discovery “radically changes”our understanding of the emperor penguin habitat by showing that populations are flexible enough to make use of the habitats available to them.
Surprising behavioural flexibility
Signs of this behavioural flexibility had been observed in the past. Some emperors breed on top of icebergs rather than on fast ice, for example – and a few colonies forego ice altogether and breed on land. This is the case for a breeding colony near Taylor glacier, where the bedrock is flat enough for the heavy penguins to navigate. “The penguins here are, in a way, lucky,” says at the Australian Antarctic Division in Tasmania: they can breed successfully regardless of the fast ice conditions. They may, however, find the rocks uncomfortably hot in summer.
Such adaptability makes sense, says Wienecke. “The Antarctic environment is fierce and greatly dynamic. If you want to survive, you have to be flexible.”
In recent decades, that environment has become far more dynamic as the global climate has warmed. For instance, , 13 colonies probably lost chicks because the fast ice began to break up before the youngsters were fully fledged. But there is some evidence that emperor penguins can respond to these problems, at least in the short term.
The Halley Bay colony provides perhaps the best example of this. Not so long ago, this was the second-largest breeding group anywhere in Antarctica, with several tens of thousands of birds. Then a lack of stable fast ice led to near-total breeding failure for three years, beginning in 2016. The colony collapsed, with just a few hundred adults remaining today. But when Fretwell and Trathan used satellite data to document this collapse in 2019, they found 55 kilometres to the south where conditions were more favourable. This more southerly location, the Dawson-Lambton colony, had comprised just a few thousand birds in 2016. It now contains tens of thousands.
It seems that, in the space of just a few years, thousands of emperor penguins abandoned the Halley Bay colony and moved to Dawson-Lambton – an astonishingly fast behavioural change. “Smaller penguins don’t really do that,” says Fretwell. Species including the 75-centimetre-tall chinstrap penguin, which lives in the South Pacific, seem reluctant to abandon historical breeding grounds even if conditions deteriorate, he says.
, also at Woods Hole Oceanographic Institution, and her colleagues have begun to incorporate this capacity to migrate into models that predict future trends in the emperor penguin population. The latest, yet-to-be-published versions suggest that under a high-emissions scenario, migration could make a significant difference to the penguin population of 2100. “It may result in up to a 7 per cent larger global population compared to models without dispersal,” says Jenouvrier.
An endangered species
A 7 per cent improvement is undoubtedly significant, but it may be cold comfort given predictions that many breeding colonies may drop to by the end of the century. Such models make clear that emperor penguins are in serious trouble despite their astonishing flexibility. To determine what more can be done to help the species, researchers have to get even closer to the birds.
Doing so isn’t easy. Even in the Antarctic summer, the weather can hamper research efforts. “I’m actually there right now,” says Zitterbart, who often spends the southern polar summer months at a research base, Neumayer Station III, that lies just 8 kilometres from the colony at Atka Bay. “I walked to the colony today, but it was very stormy and we didn’t see a single penguin.”
This may explain why so few researchers have managed to catch and handle emperor penguins. “Probably more people have travelled into space than have handled emperor penguins,” says Zitterbart.
Catching and tagging the birds can reveal invaluable information for their conservation. Most notably, Jenouvrier, Labrousse and their colleagues discovered that swim much further north, away from the Antarctic coast, than we had thought – and far beyond waters that are protected to at least some degree from commercial activities. That has led Zitterbart and colleagues to , although Wienecke points out that it will be hugely challenging to reach international agreement on such a move.
The ultimate goal would be to track individual emperor penguins over their 20-year life. This has been hard to achieve in the past, since they are essentially indistinguishable from each other to the human eye. It is for this reason that Zitterbart and his colleagues have begun chipping birds at the Atka Bay colony with RFID tags – similar to those used to chip pets – which will allow them to track the birds’ progress in the long term. By combining this with data obtained from blood samples, they may be able to identify potential genetic markers associated with the greatest breeding success, which might hint at additional heritable components to emperor penguin adaptability. This could, in turn, improve future predictions of population change.
The ECHO robot
One challenge is that the RFID tags can only be read if the birds pass within a metre or so of a scanner. The solution is a that trundles tirelessly around the colony, carrying the scanner to each penguin in turn. The robot is equipped with a depth camera and lidar to build up a 3D picture of the terrain and avoid obstacles. It uses artificial intelligence to recognise penguins and approach them, moving slowly to avoid stressing the birds. Eventually, it will be able to return to solar-powered charging stations on the ice to top up its batteries, making it almost fully independent. Zitterbart and his colleagues have been using the robot for a few years, and although they have yet to discuss it in a formal study, Zitterbart says initial testing shows that it doesn’t disturb the penguins.
The hope is that similar autonomous technology could be deployed at other colonies around Antarctica to get a sense of how the emperor penguin is faring across its entire range. That should also give us information on the health of the Southern Ocean as a whole. “Studying emperor penguins is, of course, important for the future of the species,” says Zitterbart. “But it is also important for what it reveals about this big and inaccessible ecosystem.”
Whatever the robot reveals about the penguins’ breeding habits, most researchers agree that the long-term future of the species depends on how quickly we can move to a low-carbon economy. “I think these remarkable birds have been doing their utmost for a while to adapt,” says Wienecke. But, as Fretwell puts it, their survival will be decided not by their behavioural flexibility, but by ours.
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