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What’s the state of global warming? Ask the penguins.

Inside the high-tech quest to count the birds who signal climate change

By Erick Trickey

Even in the Southern Hemisphere’s summer, shards of sea ice surround the aptly named Danger Islands off the tip of the Antarctic Peninsula. The 10 scientists and graduate students who sailed for the rocky archipelago in December 2015 didn’t know if they’d reach their destination, let alone accomplish their mission.

But the clouds and the ice parted, and the small, nimble expedition ship M/V Hans Hansson finally anchored off the coast of one of the seven islands. The biologists, zoologists, and robotics engineers rode an inflatable boat from the ship to land, looking for Adélie penguins.

Penguinologists frequently travel to Antarctica to check on the location and health of penguin populations and discover new penguin colonies — with the ultimate goal of understanding how the Southern Ocean is changing.

Satellite imagery of some of the Danger Islands had revealed the telltale pink tint of penguin guano — so much of it that the islands appeared, from high above, to be an unrecognized penguin hotspot. Even so, the team was awed by what it saw with its own eyes: penguins across the entire field of vision, clustered on gray-white rocks. The two-and-a-half-foot-tall, black-headed birds, with white rings around their eyes and little orange beaks, mingled and squatted on nests, giving the scientists wary side-eye glances.

“When we first roll up, the scale really is pretty magnificent and you’re thinking to yourself, ‘Okay, there’s a lot of penguins here,’” says Casey Youngflesh, an ecologist on the team. “Once you start adding it up day after day, it’s like, ‘Okay, on so-and-so island, there’s however many hundreds of thousands of birds.’”

The team needed an exact number, so that future researchers can measure whether the colony grows or shrinks, and why. It tried to count them by sight — but that proved overwhelming. Expecting that, a graduate student working for Hanumant Singh, a Northeastern University robotics professor who was working at the time at the Woods Hole Oceanographic Institution, had brought a set of 14-inch-wide drones, each equipped with a camera. Amid temperatures just on either side of the freezing point, the student flew the drones more than 100 feet above the Adélies to take photographs that captured every penguin and each nest. Afterward, Singh’s image-processing team did something no one had done before: They combined the photos into vast mosaics, which they ran through a machine-learning program that counted each penguin. The scientists checked the program’s work by comparing it to their sample hand counts.

Hanumant Singh, director of Northeastern University’s Field Robotics Lab, deployed drone operators to Antarctica to photograph penguin colonies, so that machine learning could count the birds precisely. Photo by Matthew Modoono / Northeastern University

The result: the team counted 1.5 million Adélie penguins on the Danger Islands — 751,527 breeding pairs, to be exact. (That count doesn’t include the pairs’ just-hatched penguin chicks, which were nestled under their parents’ feathers, or other Adélies too young to breed.) It turned out that the Danger Islands were home to more Adélie penguins — pronounced ah-delly by English-speaking penguinologists, ah-day-lee by French-speaking ones — than the rest of the Antarctic Peninsula region combined. Thanks to that discovery, a proposed marine protected area for the western Antarctic Peninsula has expanded to include the islands.

“Adélies are the most studied species in the entire Antarctic,” says Heather Lynch, an ecologist and penguin expert at Stony Brook University and an organizer of the Danger Islands expedition. “They’re a good sentinel species for what’s going on in the Antarctic. They’ve established themselves as a real metric of Southern Ocean health.”

In Antarctica and beyond, scientists don’t just study penguins for penguins’ sake, but also because their peril is a harbinger of larger changes in the Southern Ocean that will affect many other species, large and small. And not every finding is as encouraging as the discovery of the 1.5 million Danger Islands Adélies. Taken as a whole, the new penguin research shows how our rapidly warming world is changing the ocean and the animals that rely on it. The new technology also shows this: if humanity doesn’t address climate change very quickly, some species of Antarctic penguins could become threatened — and the emperor penguin, the largest and most famous of all penguins, may well go extinct by the century’s end.

That threat gives the scientists who study penguins a sense of urgency and mission. Many people find the flightless, waddling birds cute, intriguing, and even inspiring. So scientists hope that their work will sound alarms and help people see how curbing our reliance on fossil fuels could save penguins’ icy homes. Saving any species is important. And this species, with its formidable charms, is one of nature’s best advocates for itself, for Antarctica, and for fighting climate change.


The poet e.e. cummings wrote, “A poet is a penguin — his wings are to swim with.” A penguin waddling around her breeding ground is prosaic; a penguin swimming is poetry. Penguins spend 80% of their time in the waters where they live — across the Southern Hemisphere, in South America, South Africa, Australia, New Zealand, and even on the equatorial Galápagos Islands. Flightless, their wing structures have evolved to swim. They can swim for hundreds of miles in the Southern Ocean, even thousands, floating on the waves to sleep. About once a decade, a wayward Antarctic penguin turns up on the shore of New Zealand, 3,000 miles away.

Getting to know Antarctic penguins in the wild used to mean extended in-person study, usually of penguin colonies near research bases, and almost entirely in the austral summer — November to February in the Southern Hemisphere. “Until about 10 or 20 years ago, wildlife biology would have looked very familiar to Darwin,” says Lynch.

But in the past 10 years, advancing technology has created a kind of revolution in penguinology, allowing scientists to study Antarctic penguins year-round, despite their remoteness from human civilization. Drones and satellites now gaze down upon penguin colonies, counting birds and nests. So do time-lapse and sensor-activated cameras, installed and serviced once a year. Miniaturized “crittercams” taped to penguins’ feathers for a few days allow scientists to see their graceful flights through water and their hunts for tiny crustaceans and fish. Time-and-depth trackers, attached to penguin legs like tiny watchbands, track the birds’ foraging trips across the Southern Ocean. Machine-learning algorithms analyze the vast new streams of penguin images, learning from humans how to recognize penguins and their nests. Point Blue, a California-based conservation science organization, travels annually to Antarctica’s Ross Island to work with one of the world’s largest Adélie colonies, also attaching tiny “penguin Fitbits,” the size of a dime, to their legs to track their foraging swims and dives.

“My passion is, how do we take robots and technology and use them to solve problems of high social relevance or societal relevance?” says Singh, who is now director of Northeastern University’s Field Robotics Lab. “Suddenly, with the use of these robots, we’re now collecting lots of data that’s actionable. A lot of our end users are used to annotating these images by hand, because they’re used to getting 100 images. When you suddenly give them 100,000 images, they can’t do that anymore.” Instead, Singh’s drones collect so many photographs that scientists need machine learning to sift through them all. “We’ve gotten so good at getting this data now that we have to use these new techniques.”

“Given climate change and global warming, we are trying to understand what will happen with the penguins. Where are they going to move? Where are they going to forage?”

Andrea Raya Rey, an ecology professor at Argentina’s University of Tierra del Fuego

For their part, penguins often take more interest in the humans than in their technology. That was the case, at least, in January 2020, when researchers from the Field Robotics Lab arrived with drones to count chinstrap penguins on Elephant Island, 160 miles north of the Danger Islands.

Some of the 106,000 chinstrap penguins on the island pointed their black beaks to the sky to look up at the little dot 100 feet above them, but they soon turned their attention back to land. When Yang Liu, then a graduate student in the lab, sat down on the island to eat, one especially curious chinstrap walked up to him, bent down, and pecked Liu’s shoe with his beak.

The humans tried to give the penguins space, but sometimes they had to pass through a penguin colony to do their work. As they treaded within inches of the 2 1/2-foot-tall chinstraps, some of the birds ignored them — but others tried to shoo off the interlopers. The chinstraps honked, pecked at the researchers’ legs, and even beat them with their flippers. “They can get aggressive,” says Vikrant Shah, another Northeastern graduate student on the expedition. “They hang onto your pant legs by their beak.” One reason: The penguins were protecting their nesting chicks, fuzzy gray and three weeks old.

Chinstrap penguins are named after the black line that frames their face just above the neck and connects to the black tops of their heads. They’re loud — their throaty honks can combine to sound something like a pack of barking dogs. “If you are in a large colony,” Shah recalls, “you would see one side start to go ‘yak, yak, yak’ — and then that would, just like a wave, go through the whole colony.”

Singh had deployed Shah and Liu to help several scientists conduct the first census of the island’s penguins since 1971. The team hitched a ride on a Greenpeace boat, the M/V Esperanza. Among their shipmates: actors Marion Cotillard and Gustaf Skarsgård, who visited several islands in the Southern Ocean to draw attention to how climate change has affected Antarctica.

The penguin census results confirmed those warnings. The chinstrap penguin population of Elephant Island had dropped from 122,500 breeding pairs in 1971 to 53,000 in 2020, a 57% decline. Much of that population collapse is likely recent. A survey of five Elephant Island chinstrap colonies, by the same December 2015 expedition that visited the Danger Islands, showed that the colonies had declined by 26% to 38% in just four years. Chinstrap populations “are collapsing quite rapidly,” says Lynch, who worked with Singh to plan the Elephant Island expedition and co-authored a study of the global chinstrap population in 2020. The paper found that across Antarctica and beyond, 45% of chinstrap colonies studied in the 1980s have declined, while only 16% have grown.

Scientists are using the new counting technology to pinpoint the exact reasons for the decline. “We’re trying to understand the relative importance of climate change as a cause of the population changes we see, versus fishing and tourism,” says Lynch. So far, she says, research suggests that tourist visits don’t cause penguin populations to drop. Fishing has more effect. Penguins on the Antarctic Peninsula eat krill: pink, shrimp-like crustaceans about the size of a large paper clip. Seals and whales eat them, too. “Pretty much everything in the Antarctic eats krill or eats something that does eat krill,” says Lynch. The international krill-fishing industry — which supplies fish food for aquariums and krill-oil dietary supplements for humans — competes with penguins for their prey, and scientists are trying to figure out how much that hurts penguins. Research insights could lead to new restrictions on large-scale commercial fishing under the Antarctic Treaty.

But climate change is emerging as perhaps the biggest cause of penguin population decline. “Rain has a really devastating impact on penguins,” says Lynch. “It can snow all at once and penguins are happy, but as soon as it rains, that soaks their chicks, and their chicks very quickly die.” As the Antarctic Peninsula warms, it’s getting more rain and less snow. “Air temperatures are hovering right around freezing, somewhere between 30 and 35 degrees on a typical day,” Lynch says. “Even a very small amount of warming tips that balance from a snow-dominated environment.”

Climate change doesn’t just hurt penguins on land. Even more important is what happens to them in the ocean, where they swim and forage for food. “Climate change is changing the distribution and the timing of sea ice,” which is a nursery for krill, says Lynch. When sea ice declines, forms too late, or breaks up too early, that hurts the krill population. “We think that there’s less krill in the ocean for the penguins, or the krill that is there is just not in the right place,” she says.

That’s a direct threat to species like emperors, made famous in movies like Happy Feet and the documentary March of the Penguins. Standing almost four feet tall and weighing about 88 pounds, they’re listed as “near threatened” by the International Union for Conservation of Nature, and they’re under consideration for inclusion in the U.S. Endangered Species Act.

Stéphanie Jenouvrier, a biologist at the Woods Hole Oceanographic Institution on Massachusetts’ Cape Cod, has studied emperor penguins for 20 years, investigating how they respond to climate change, especially declines in sea ice. She began by studying the emperor penguin colony on the Pointe-Géologie archipelago, near the French Antarctic research station Dumont d’Urville, named for the French explorer Jules Dumont d’Urville, who discovered the area in 1840. (Adélie penguins are named after his wife, Adèle.) Since then, Jenouvrier has collaborated with other penguinologists to study Antarctica’s entire emperor penguin population via satellite imagery.

Though the Pointe-Géologie emperor population has been stable in recent years, it has never recovered from a fast decline in the 1970s as sea ice grew more scarce. That’s a harbinger of what a warming Antarctica will mean. Jenouvrier’s work at Pointe-Géologie, combined with satellite-based estimates about the continent’s other emperor colonies, has resulted in a chilling prediction: If sea ice declines at the rate projected by climate models, emperor penguins will be extinct by the end of the century.

To prevent that, Jenouvrier says, the world would have to meet the goal set in the 2015 Paris Climate Accords: limiting greenhouse gas emissions enough to keep global warming to no more than 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, compared to pre-industrial temperatures. “It’s a huge commitment to mitigate the effect of climate change,” Jenouvrier says. “We are not on the route to meet those agreements. This is the only way we can save emperor penguins.”


Not every penguin species stands to suffer as a result of warming seas. For gentoo penguins, native to the Antarctic Peninsula and other islands north of Antarctica, a warming climate means more area for breeding and eating. Gentoos, who have bright red-orange beaks and big white patches above their eyes, are the world’s fastest-swimming birds, capable of reaching 22 miles per hour. They can dive hundreds of times a day to forage for prey, to depths of up to 600 feet.

“Gentoo penguins are actually a winner when it comes to climate change,” says Fiona Jones, a British zoologist who studied penguins for her doctoral thesis at the University of Oxford. “We’re seeing their population shift down the Antarctic Peninsula into more southern regions, which previously weren’t hospitable to them because they were too cold and too icy.”

Some of the latest research on gentoos is being conducted by Andrea Raya Rey, an ecology professor at Argentina’s University of Tierra del Fuego. She’s deployed 40 cameras on islands off South America’s southern coast to capture the habits of penguins, cormorants, and doves. She records the sounds penguins make to monitor their behavior, takes blood and feather samples to deduce where in the ocean penguins forage, and also tracks their foraging directly with GPS devices and depth data loggers, using machine learning to predict their migration. “Given climate change and global warming, we are trying to understand what will happen with the penguins,” Raya Rey says. “Where are they going to move? Where are they going to forage?”

Raya Rey and the University of Oxford penguin researchers have found that the changing climate is affecting gentoos and other penguins in more ways than just migration. For instance, they’ve learned that gentoos are breeding earlier in the year now because of climate change. “So you have penguin chicks when there is not enough food,” Raya Rey says. “Usually, penguins have their chicks in summertime, when there’s more food in the ocean.” That could cause penguin populations to decline.

A few times a year, Raya Rey also tapes a camera to a penguin’s back, for a rare gentoo’s-eye-view of the ocean. In one video, taken in December 2021, a male gentoo penguin zooms through the water off Tierra del Fuego, Argentina, with a crittercam taped to his back and plunges into a school of sardines. CHOMP! He snags a sardine in his beak. The fish squirms. The gentoo gulps it down. The camera catches glimpses of other penguins, as well as diving cormorants and an albatross — all swooping to gorge themselves on the sardine feast.

Raya Rey is one of several penguinologists around the globe who processes her vast arrays of penguin images with the help of Penguin Watch, a citizen-science project. The University of Oxford research team travels each year to Antarctic penguin colonies to count nests, fly drones, and replace batteries and memory cards on the penguin-cams they’ve installed there. With 100 cameras in Antarctica and on nearby islands, each taking a picture every hour, they have more than a half-million images to process per year. “As a tiny team, we just couldn’t possibly analyze all of that data manually,” says Jones. But crunching the data is possible because 50,000 registered Penguin Watch volunteers have tagged penguins in 6.5 million images since 2010. “It’s really easy!” Jones says. “We encourage children to do it.” The human counts help train Pengbot, a computer vision algorithm that uses machine learning to better recognize penguins in images. “We call it Pengbot, because why not?” Jones says.

It’s easy for Penguin Watch to find volunteer penguin-taggers. “People love to learn about penguins,” Jones says. “They’re a group of animals that really capture people’s imaginations and their hearts. They’re very charismatic.” Ecologists hope that a love for penguins will translate into support for conserving their homes. “All of these things contribute to people becoming advocates for the environment,” Jones says, “and inspire them to maybe take part in their own conservation initiatives.”

Visiting penguins in a well-run zoo can also inspire humans to help save the species and, by extension, the planet. In the Northern Hemisphere, the only places to see penguins’ waterborne grace are penguinariums like the Detroit Zoo’s Polk Penguin Conservation Center, which claims to be the world’s largest penguin facility, thanks to its 326,000-gallon swimming tank. The zoo is home to 78 penguins: 20 gentoos and four chinstraps, 18 kings, 18 macaronis, 17 rockhoppers, and one hybrid, a macaroni-rockhopper. (“I didn’t know they could get together,” I told Jessica Jozwiak, the Polk Center’s supervisor, when she described the single cross-breed penguin to me. “We didn’t either,” she replied. “It was a real sneaky, sneaky thing.”)

On the ground level, five types of penguins hop, bottom-heavy, across rocks meant to imitate Antarctic and South American landscapes. But the real wonder comes when human visitors descend to the building’s lower level, past an exhibition about explorer Ernest Shackleton’s ill-fated Antarctic expedition, and see the penguins behind a giant glass wall, gliding past like birds in flight, in water bluer than sky. 

The zoo’s 20 gentoos are gregarious and active, always on the move. Fun-loving, they’ll bat around tennis balls attached to PVC pipe. Gentoos greet each other with an open-mouth scooping motion.

“They’ll bow their heads down a bit,” says Jozwiak. “They also hiss at you if they’re not happy with you being too close.”

The Polk Center’s penguins are a huge draw; a half-million visitors saw them in summer 2018 alone. On the day in 2022 that I visited with Jozwiak, a small crowd of zoogoers started chatting. Just by staring at the glass, some had gotten to know how gentoo behavior is different from other penguins’. “They’re very sociable — they get into everybody’s business,” a woman standing at the exhibit said to Jozwiak. “The kings will be over here, chilling,” she added, “and then the rockhopper and the macaronis are over in the corner. Then here come the gentoos — like, ‘Hello! I want to hang out with you guys!’”

Meanwhile, at the bottom of the world, tourist fascination with remote Antarctica and its penguins is growing. In the 2019-2020 austral summer, just before the pandemic, 74,400 tourists visited the frigid continent, double the number that came four years earlier. Tourist visits to emperor penguin colonies quadrupled during the same time. Though COVID-19 wiped out the 2020-2021 Antarctic tourist season, several cruise-ship companies began sailing to Antarctica again in the 2021-22 austral summer.

Indeed, like other penguinologists, Jones often gets to Antarctica by hitching a ride on cruise ships. “We give onboard lectures to tourists,” she says, “and hopefully inspire them to become Antarctic ambassadors.”

Scientists hope that people who make a personal connection with Antarctic penguins will become advocates for taking action against climate change. “If you care about a penguin,” says Raya Rey, “you are going to be more careful with your use of the planet Earth.”

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Erick Trickey is Experience's deputy editor. He has written for Politico Magazine, The Washington Post, Boston magazine, and more.

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