ADVERTISEMENT

Heat Exhaustion: Has the Adelie Penguin Met Its Match?

After flourishing for thousands of years in the harshest environment on Earth, the Adelies in one part of Antarctica have encountered an obstacle they seem unable to overcome--us
adelie-penguins



Courtesy of Fen Montaigne

Editor's Note: The following is an excerpt from Fen Montaigne's book, Fraser's Penguins: A Journey to the Future in Antarctica.

On December 3, 1959, Richard L. Penney, a pioneering penguin researcher, snatched five male Adélie penguins from their rookery on Wilkes Land, in eastern Antarctica. He affixed numbered bands to their flippers, placed the Adélies in cloth bags, and had them flown halfway across Antarctica to McMurdo Sound, on the Ross Sea. There, they were released.

Ten months later, three of the five returned to the Wilkes Land colonies from which they had been taken. The penguins had swum 2,400 miles along the Antarctic coast, passing many Adélie rookeries along the way. Their average speed was eight miles per day. What was most remarkable was that the birds managed this feat after being flown overland and turned loose in a place they had never been before. They had made a beeline for their natal colonies and, following a route they had never traveled, wound up in the same rookery where they had been abducted nearly a year earlier.

This sophisticated homing ability is but one of the remarkable traits of the Adélie, the classic tuxedoed penguin that has amused, fascinated – and fed – explorers and scientists in Antarctica for nearly 200 years. Over the decades, penguin scientists and casual observers have seen Adélies pull off similarly astounding, or quirky, feats, from mating in howling blizzards, to surviving leopard seal attacks that left the penguins nearly torn in half, to entertaining themselves by vaulting onto icebergs, hitching a ride for a few hundred feet, and then sliding off as if on an amusement ride.

Now, after flourishing for thousands of years in the harshest environment on earth, the Adélies in one part of Antarctica have encountered an obstacle they seem unable to overcome: Us. Thanks largely to our emissions of greenhouse gases, the western Antarctica Peninsula has warmed faster than virtually any place on the planet, rendering sea ice-dependent Adélies in some areas unfit to live in an ecosystem where all forms of ice, on land and in the Southern Ocean, are in retreat.

That parts of Antarctica have become too warm for Adélie penguins would surely have astounded earlier explorers who suffered so greatly from the cold, and who marveled at the resilience, and eccentricities, of these seabirds.

One of the continent's earliest explorers, James Clark Ross – the Englishman who discovered the Ross Ice Shelf – remarked on the stirring sight of Adélies arcing in and out of the water during the migration to their home colonies. In 1841, he wrote of the "wonderful instinct, far beyond the powers of untutored reason, that enables these creatures to find their way . . . several hundred miles to their usual place of resort."

Locked in the ice on their ship, the Endurance, after a long, dark winter, Ernest Shackleton and his men were gladdened by the sight of Adélies, seals, and whales "disporting themselves in the leads" between ice floes. When three Adélies marched solemnly up to the ship, one crewmember pulled out his banjo and began plucking "It's a Long Way to Tiperary," which "the solemn-looking little birds appeared to appreciate," Shackleton reported. The bagpipe, however, was another story, and when a Scottish member of the expedition began to play the national instrument, the Adélies "fled in terror and plunged back into the sea," according to photographer Frank Hurley.

Having spent five months in Antarctica working on the field team of ecologist and penguin expert, Bill Fraser, what most impressed me was the elegantly instinctive behavior of these knee-high penguins. After migrating hundreds of miles from their winter feeding grounds, they marched off the ice in the austral spring and – even though their nesting territories were concealed under snow – headed to the very colonies where many were hatched or had raised chicks before. There the Adélies stood or lay patiently until the snow melted, exposing the pebbled ground underneath. If a mate from the previous season survived the winter, the pair frequently was reunited. Together they patiently constructed a cup-shaped nest of stones. They copulated. They took turns incubating two eggs, with the liberated penguin heading for feeding grounds in the Southern Ocean, where it gorged on krill before returning to relieve its partner. Together, the couple guarded the chicks, and when their offspring's demand for nourishment became overwhelming, both parents took to the sea to feed. Upon their return, the parents recognized their chicks not by sight but by voice, identifying them by the slightest variations in their raspy calls.

Finally, as the chicks reached adult size, losing their down and gaining feathers, the entire raucous yet well-ordered process crescendoed. Sensing they could no longer continue to feed full-grown chicks and keep themselves alive, the adult Adélies simply took off. The adolescent Adélies clustered in packs and contemplated the fact of their abandonment for a day or two. Then, their hunger growing, they clumsily made their way to the shoreline. They stared at the Southern Ocean for hours, perhaps days, until making the ultimate instinctual leap of faith: They dove in.

One morning, after observing this round of reproduction at close range for four months, I walked into the galley at Palmer Station, a U.S. science base on the western Antarctic Peninsula, and was struck by a saying on a calendar at the head of the food line. It was from Pythagoras, and it read, "Astonishing! Everything is intelligent!"

Well, almost everything. The long arm of industrial society has reached all the way down to the world's coldest and most isolated continent, altering the environment of the Antarctic Peninsula. Over the past 60 years, winter temperatures in the northwestern part of the peninsula have soared by 11 degrees F. Year-round temperatures have risen by 5 degrees F and the surrounding ocean is warming. Roughly 90 percent of the region's glaciers are in retreat. And, most important for a sea ice-dependent species like the Adélie penguin, the ocean along the western Antarctic Peninsula is now frozen three fewer months a year than in 1979.

The sharp reduction in sea ice duration has deprived the region's Adélies of a crucial platform in winter to reach the most productive foraging areas. (In this sense, the iconic symbol of the Antarctic is suffering from the same loss of sea ice that is afflicting the Arctic's iconic creature, the polar bear.) The steady disappearance of sea ice also has led to an apparent reduction in the prime source of food for Adélies  — Antarctic krill, the shrimplike zooplankton whose life history is intertwined with sea ice. Likewise, the Antarctic silverfish — another sea ice-dependent species and once an important source of food for the Adélies around Palmer Station — is becoming increasingly scarce in the region.

In addition, now that sea ice blankets the Southern Ocean off the western Antarctic Peninsula far less than before, more water is evaporating and forming precipitation, largely in the form of snow. That has led to heavier spring snowfalls in many Adélie colonies, which, when the snow melts, inundates Adélie eggs and addles them. In recent decades, as the Antarctic Peninsula has warmed around him, Bill Fraser has pieced together these myriad factors that have caused Adélie populations in his study area to decline by more than 80 percent, falling from roughly 35,000 breeding pairs in 1974 to 5,600 today.

"Here you have this unbelievably tough little animal, able to deal with anything, succumbing to the large-scale effects of our activities," Fraser told me. "And that's the one thing they can't deal with, and they're dying because of it."

Antarctica's Adélie penguins, numbering some 2.5 million breeding pairs, are hardly facing extinction. But what is happening along the Antarctic Peninsula is a sign that global warming has at least breached the world's coldest continent, where ice reaches a depth of three miles in places and Earth's coldest temperature, -128 degrees F., was recorded. As for all the world's sea ice-dependent species, continued warming will ultimately be bad news for the Adélies and that other well-known Antarctic penguin, the emperor. A recent study warned that should global temperatures rise 3.6 degrees F above pre-industrial levels, three-quarters of Antarctica's Adélie penguins "are in jeopardy of marked decline or disappearance, largely because of severe decreases in pack-ice coverage."

Why should we care? For starters, if the coldest parts of Antarctica begin to melt in earnest, global sea levels could rise many feet. World weather patterns will also start to change, as a frigid Antarctic continent and the icy ocean currents that surround it play an important role in global atmospheric and oceanic circulation.

On another level, the gradual melting of the earth's ice zones, which have been a fixture of human civilization for thousands of years, is a disturbing phenomenon. So is the disappearance of the creatures that inhabit these polar and glaciated regions. None is more beloved than the Adélie penguin, whose upright bearing and almost human demeanor have charmed visitors to Antarctica for almost two centuries.

"All the world loves a penguin," wrote Apsley Cherry-Garrard, the legendary Antarctic explorer who participated in Robert Falcon Scott's 1910-1913 expedition to the South Pole. "Had we but half their physical courage none could stand against us. [They are] fighting against bigger odds than any other bird, and fighting always with the most gallant pluck."

Rights & Permissions
Share this Article:

Comments

You must sign in or register as a ScientificAmerican.com member to submit a comment.
Scientific American MIND iPad

Give a Gift & Get a Gift - Free!

Give a 1 year subscription as low as $14.99

Subscribe Now >>

X

Email this Article

X