What Antarctic Killer Whales Can Teach Humans About Climate Change

The giant mammals are extremely vulnerable to changes in the ecosystem, making their health a good barometer for the state of the environment.

A large group of Type B2 killer whales (John Durban / NOAA / Holly Fearnbach / SR3)

They stood on the top bridge of the cruise ship National Geographic Explorer, peering through binoculars at the vast icy Weddell Sea. It was a summer afternoon in February in Antarctica, the air a balmy 32-or-so degrees Fahrenheit, and John Durban and Holly Fearnbach, biologists with the U.S. National Marine Fisheries Service, had spotted killer whales in the distance.

The only question was, were these the Type B2’s, with their gorgeous gray-and-white coloring and their culinary fondness for Gentoo penguins—one of only three kinds of killer whales found in the Antarctic Peninsula? Or another type of killer whale unique to these cold deep waters? From miles away it was hard to tell. The rest of us spectators on the ship, far from our native habitats of Texas, England, and Kenya, gazed out at the ice floes and the foggy horizon splashed with blue, wondering too.

The scientists were on board thanks to a grant from the Lindblad Expeditions-National Geographic (LEX-NG) Fund. The fund aspires to protect the ocean’s last pristine areas through research, conservation, education, and community-development projects in the company’s far-flung destinations.

For Durban and Fearnbach, who are based in sunny La Jolla, California, the fund has buoyed their research in Antarctica. While they also study orca and humpback whale populations in the Pacific Northwest, the North Atlantic and Alaska, on these trips they’ve been able to observe killer whales in perhaps the most inaccessible place on the planet. Since 2011, the scientists have made several voyages a year to the frozen continent on the Explorer, using the ice-cutting, refurbished Norwegian ferry to follow the whales.

On the trip in early February, the scientists were joined by 148 passengers and a flock of naturalists. For those paying hefty sums to see Antarctica, the 10-day voyage was like a floating science classroom. In the lounge, naturalists lectured on such pertinent topics as “Know Your Penguins,” “What Does Ice Tell Us About Climate Change?” and a Belgian expedition’s epic discovery of the Gerlache Strait.

Durban and Fearnbach gave several talks about their work in Antarctica, and how the health of killer whales is a barometer of the continent’s rapidly changing environment. Their research has been especially revelatory. Until as little as 20 years ago, scientists used to believe that Antarctic killer whales were all alike. But Durban, his colleague Bob Pitman and others took small skin samples of whales, analyzed their DNA, and ended up discovering that there are five distinct types, each with its own prey preferences, hunting techniques, and habitats. Durban and his colleagues are proposing that they may be separate species. This means that each type of killer whale will adapt to climate change in different ways—some likely better than others—largely depending on their food supply.

The enormous Type A’s, which are a striking black and white, feed on minke whales and perhaps elephant seals. The B2’s, which are the smallest and most plentiful, typically frequent the Gerlache Strait, munching on gentoo and chinstrap penguins and probably fish. The B1s, which are a dazzling gray and white, dine on seals. When they hunt, the clever whales band together and literally make waves to wash seals off ice floes. “They are my favorite animals,” said Durban during their talk.

Four juvenile, Type B2 killer whales in close pursuit of a Gentoo penguin
(John Durban / NOAA / Holly Fearnbach / SR3)

It’s not exactly easy to spot killer whales in the Antarctic seas, where the horizon can be an endless expanse of whites and grays and mesmerizing teal-blue ice sculptures. The creatures are mostly underwater, and race through the seas at a brisk 55 miles per hour. When Durban and Fearnbach do spy them, or get a tip from the sharp-eyed crew on the bridge that whales are in sight, the scientists chase after them in a Zodiac—a small, black rubber motorboat—taking photographs and collecting data. The photos help them identify individual whales and keep close track of their health from year to year. They can also pinpoint where in the vast Antarctic waters the whales are most likely to be, and how stable the various populations are. Although they already know a lot, they want to learn more about what the insatiable animals eat. That will tell them if the warming environment is threatening their food sources.

There’s abundant enthusiasm for their research on the ship. Passengers and naturalists have contributed thousands of photographs of killer whales to the scientists. Counting their own photographs snapped from the Zodiac and from the Explorer’s decks and bow, they’ve amassed nearly 80,000 images of the little-observed animals.

In the past six years, they’ve gained tremendous insights into the enigmatic cetaceans. Using tiny satellite tags affixed to whales that relay their movements, Durban and Fearnbach were the first to document Antarctic whales making a speedy, 5,000-mile trip to the warmer waters of the subtropics and back, apparently to shed their algae-encrusted skin. They recorded the deepest dives—more than 2,000 feet—of any killer whales in the world. They’ve seen feeding behaviors few scientists have: a killer whale dangling an elephant seal in its mouth, another type of killer whale pursuing pretty Adélie penguins.

In early February, the researchers had already been out for two weeks traversing the Southern Ocean and Weddell Sea, where Ernest Shackleton’s ship Endurance famously got trapped in ice in 1915, trying to fathom more about the role of killer whales in the continent’s rapidly warming environment.  With news of the ever-widening crack in the nearby Larsen C ice shelf, their quest seemed especially relevant.

Larsen C, a mass of ice the size of Vermont and New Hampshire, is melting because of warming from climate change. Because killer whales need sea ice to survive, this means their habitat is changing in profound ways. Durban and Fearnbach were eager to answer some vital questions. How healthy were the Antarctic whales? What were they feeding on? How much prey were they eating? Were the researchers seeing animals they’d photographed in previous years? Or had some whales vanished, perhaps died?

These questions matter because killer whales are easily affected by changes in their environment, and heavily shape it, too. Killer whales live as long as humans do, but produce very few calves; each one’s survival is critical. As the continent’s top predator, they’re especially vulnerable to changes in the food chain, like contaminants, or overfishing of krill, a pink, shrimp-like crustacean that humpback whales and other species devour. “In order for them to be healthy, the ecosystem needs to be healthy,” said Durban.

They also eat a ton, so they exert a huge influence on Antarctica’s spectacular array of marine life, including Weddell seals, minke whales, and several species of penguins. As the climate changes, the researchers are trying to understand how killer whales are affecting prey populations.

That afternoon when they spied the roaming whales, they dashed inside and approached Captain Oliver Kruess. Did they have time to go out in a Zodiac and take photographs? The ship was on a strict schedule, set to be at Mikkelson Harbor, which was hours away on the east side of the Peninsula, by morning. There was some negotiating among the scientists, the captain, and the ship’s expedition leader, Lucho Verdesoto Yumiseba, who was in charge of the daily itinerary. The researchers were told they had 45 minutes. Kruess, who saw the whales go, gave them some handy navigation advice. “It was a great example of the support we get on the ship,” said Durban. “We almost didn’t have time.”

They scrambled into a Zodiac with their colleague, Leigh Hickmott, and shot out from the starboard side toward the whales. A gaggle of passengers in orange hooded parkas lined the decks and bow in the freezing air, taking photos. Soon after they launched, they made a thrilling discovery. The seven whales were not B2’s, but the even more elusive Type B1’s. During two expeditions in the previous weeks, they had not seen them once. “They are probably the hardest killer whales to find in the world,” said Durban. “They live in the pack ice, so it’s hard to go where they live. They can do 150 miles a day.”

The hexacopter allows researchers to collect aerial images of the animals.
(Courtesy of Leigh Hickmott)

While the Zodiac idled, they launched an unmanned hexacopter into the sky.  The high-tech drone, which is outfitted with a tiny camera, resembled a toy. Fearnbach, her head under a “lucky” towel that’s been with them all over the world, looked at a computer monitor, guiding Durban as he flew the hexacopter 100 feet above the whales, taking pictures. The drone carries an altimeter to record height, so they can scale photographs with startling precision to measure the whales. “We can tell a change in their fatness down to the level of a centimeter,” Durban said. “For a large whale that might weigh dozens of tons, that’s amazing resolution.”

In 2014, they were the first to use an unmanned drone in photogrammetry—the art of measuring animals from aerial images—on any kind of whale. Researchers have long used photographs to identify whales using natural markings; scars on their dorsal fins, the colors of their saddle patches. But the drone has considerably upped their game, enabling them to track individuals’ body condition and growth over time, and get better population estimates.

With a grant from the LEX-NG Fund, they first flew the hexacopter in Antarctica in early 2016. Over their three voyages, they’ve taken more than 4,600 aerial images.

“We used to do this kind of work but from a helicopter or a fixed-wing aircraft,” said Durban. “We’d be several hundreds of feet up so the pictures weren’t as good. It has increased the quality of what we do.”

The hexacopter, which is about as light as a toaster and adaptable enough to fly in remote areas, also allows them to collect more data without disturbing the whales. The highly social animals don’t seem to notice it’s there.

From that fresh perspective, they’ve seen some startling behaviors in Antarctic waters. Grandmothers giving food to their grandchildren. Sick whales unable to dive, lingering at the surface. Whales swimming close enough to touch.

On their first day out the week before, they were floating in the Weddell Sea when they spied something they’d never seen. A group of 25 killer whales—Type B2’s—were rubbing their bellies on icebergs to clean their skin. Because of the freezing waters, Type B whales develop diatoms, a kind of algae that turns their skin yellow. “It was remarkable,” said Fearnbach.

One night, as passengers chatted and sipped cocktails in the lounge, Durban and Fearnbach did a slide presentation. The two met studying killer whales in Alaska in 2005, when she joined his research team. They’re both now 40 and married. He’s tall and barrel-chested with a short reddish beard, while she’s petite with long light-brown hair. As they spoke, the $20,000 hexacopter—nicknamed “Chimo” for a white killer whale captured in 1960s—sat propped prominently on a table. “I can guarantee you haven’t seen killer whales like you saw today,” said Durban, showing an aerial photo of the mercurial B1s.

Remarkably, little is known about Antarctic killer whales, although they are more plentiful here than anywhere in the world. Over many cruises in the early 1980s, Japanese ship surveys estimated the population at 25,000. But that’s hardly precise. Their research vessels, with good reason, failed to count whales in the treacherous pack ice. Durban and Fearnbach hope to improve the accuracy of the count, by getting abundance estimates in smaller areas in the Antarctic Peninsula.

Each hexacopter flight brings new information. Killer whales usually travel in pods of 50, and remain with their family groups their entire lives. By tracking them over time, the scientists hope to discover how climate change is affecting their health. How adaptable is each species to the shifting ice conditions? Some females they’d seen one afternoon were skinny and sick, a worrisome sign. In the lounge, Durban showed a photo of a B1 female and her calf. “One of the shocking things for us—this whale is very very thin,” he said of the mother. “It’s skin and bones. It doesn’t have much blubber.”

The hexacopter hovering above a humpback whale in Antarctica
(Courtesy of Leigh Hickmott)

Later, Durban said, “Normally that type of whale is very fat. Immediately when we got in the boat, they were behaving like they were looking for food. They weren’t as energetic as normal. That one female was in terrible shape and couldn’t dive with the rest of the group.”

Females care for and feed males and their offspring first, so mothers are typically the last to eat. It’s possible the one female was ill, and couldn’t travel to find more food. Or it could signal a problem in the food supply. On previous trips in Antarctica that season, they’d seen other females in poor condition. “To me the bottom line is we’ve got to do more of this,” said Durban. “We’ve got to look at how widespread that is in the bigger population. Not just one group. We can’t take it for granted they’re healthy. We know we’ve got an ecosystem that has significant changes.”

With science funding threatened—including programs to mitigate climate change—Durban isn’t sure how their research will fare. The White House wants to slash 17 percent from the National Oceanic and Atmospheric Administration’s budget, the agency for which he works. “We’re not in a great position,” he said.

In past few years they’ve had to get creative. “We’ve become very good at collaborating, seeking diverse funding sources. That’s a model we’re going to have to continue.”

As far as the world’s largest predator goes, they have a ton of questions. It’s still unclear what the primary prey species is for Type B2 killer whales. Their previous research has shown the animals frequently dive as deep as 700 meters, deeper even than gifted swimmers like penguins. But what are they eating down there? If the Antarctic Peninsula continues to warm and the ice continues to melt, how will killer whales survive these changes? Already, one of their food sources—Adélie penguins—has declined in several areas around the peninsula. At Palmer Station, one of three U.S. scientific bases in Antarctica, the Adélie population has been decimated.

On the last day of the expedition, the scientists headed out in the glittering waters and ice towers just outside Paradise Bay, and disappeared. Hours later, they appeared in the gray early evening off the bow near a pod of Type B2’s. A sea of dark fins knifed through the black water, eliciting gasps, as passengers on the bridge counted them aloud. Later, securely back onboard, Durban and Fearnbach announced the final tally. There were 40 in the pod, a reassuringly healthy number.

Editor's Note: The images included in this story were collected during research conducted under NMFS Permit No. 19091 and Antarctic Conservation Act Permit ACA 2017-029.