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Another Bad Year for Penguins

Carol Kaesuk Yoon New York Times Service
Thursday, June 28, 2001

Climate Change, Scientists Say, Is Wiping Out These Flightless Birds

NEW YORK Harry's habits were as predictable as clockwork, so when he did not return from his last ocean voyage as expected, Dee Boersma knew something was wrong.

"We had signals until Dec. 6," said Ms. Boersma, a penguin researcher at the University of Washington in Seattle who encountered Harry - a penguin outfitted with his own satellite transmitter - at a nesting area at Punta Tombo, Argentina, which he left to forage at sea while his mate took her turn on their eggs. "Then we never heard from him again. We looked for him to come back every day. We just don't have adult birds disappear like that."

But last winter, the summer breeding season in the Southern Hemisphere, Magellanic penguins like Harry did disappear. Thousands washed up dead on the beaches north of Punta Tombo. Many abandoned their nests, leaving chicks to starve. Among the survivors, many were in bad shape, having difficulty finding the fish they needed to sustain themselves.

"This is the worst year ever," said Ms. Boersma, whose 18 years studying the colony has been supported by the Wildlife Conservation Society. "And we keep getting a lot of bad years."

Researchers say the Magellanic penguins at Punta Tombo, which have steadily decreased in number for more than a decade, are not alone. Around the world, many penguin populations are declining, researchers say, and evidence is mounting that global warming, whether natural or human-induced, is a prime cause.

Unless things change, they say, the outlook for some of these penguin species will be grim. Ten of the world's 17 penguin species are already listed as threatened or endangered. Though a few species are thriving, "penguins, in general, are experiencing some really serious problems," said Lloyd Davis, penguin biologist at the University of Otago in New Zealand. "They are in trouble."

In addition to climate change, Mr. Davis said such problems as overfishing and oil spills threatened these flightless birds. Penguins' best hope for overcoming these many obstacles, scientists say, may be their abundant adorability and the protection and money it can bring.

One typically thinks of penguins as waddling about atop miles of featureless ice, but many of the penguins at greatest risk are those species that have strayed farthest from the South Pole. The endangered Galapagos penguin, a tropical species, is also one of the rarest. Found only on those islands off Ecuador, the birds have been hard hit by rising temperatures. Ms. Boersma and others have found that the warmer the waters, the more the birds struggle to find food and to breed. In the warmest years, birds can fail to breed altogether and large numbers of adults can die of starvation.

Two other penguin species, the Magellanic and Humboldt, also suffer as waters warm. Since 1987, the number of Magellanic penguins at Punta Tombo has declined by 30 percent. It remains the world's largest colony of the species, still numbering in the hundreds of thousands, but, as with other penguins, the downward trend has researchers worried.

"If we get a series of intense El Niños, they're going to disappear," Patricia Majluf, conservation biologist at WildlifeConservation Society, said of the colony of Humboldt penguins she studies, whose numbers are also dropping. "We lost half during one bad El Niño and these are very slow breeding birds."

El Niño is a phenomenon in which the waters of the eastern tropical Pacific warm up, a change that can drive fish and other penguin prey far from colonies. The result can range from decreased egg sizes or deaths of chicks to, in a few cases, large-scale deaths of adults. In cooler La Niña years, colonies can begin to recoup their losses. But in recent decades, the number and intensity of El Niños has increased while La Niñas have declined.

As for Harry and the other dead or missing penguins, researchers now suspect that they succumbed to a biological toxin like a red tide and, again, scientists say the evidence points to climate change as the culprit. Such toxic blooms are associated with warming ocean waters.

Ms. Boersma said she got her first inkling that biological toxins might be at work when a freshly dead penguin floated ashore this winter. "It had an empty stomach that looked like it had been washed with acid," she said, adding that otherwise it seemed well fed and healthy. "He looked fine, except that he was dead." Other die-offs, also suspected to have been caused by biological toxins, have hit penguins elsewhere.

"In 1990, over half the known yellow-eyed penguins died from some mysterious disease," said John Darby, a seabird conservationist who is now retired from the University of Otago. He has studied endangered penguins in New Zealand for 22 years. Mr. Darby said he and colleagues believe a biological toxin killed them as well.

Yellow-eyed penguins are unusual because they require forest for nesting, putting them near New Zealanders who have logged to make way for farming. In other areas, penguins must compete with fishing industries. Oil spills have killed many penguins and in Peru the Humboldt is at risk because it is considered a good meal by people near the colonies.

Even the penguins in remote Antarctica, which tend to be doing better in terms of absolute numbers, can suffer declines when the bitterly cold seas warm.

Christophe Barbraud and Henri Weimerskirch, from the National Center for Scientific Research in France, reported in the journal Nature last month that warming seas and a decline in sea ice were linked to a 50 percent drop in numbers in a well-studied population of emperor penguins over the last 50 years.

In what may be the best understood of penguin declines, Wayne Trivelpiece, director of seabird research for the United States Antarctic Marine Living Resources program, and colleagues have studied Adelie penguins. What researchers have discovered is that as the seas have warmed in recent decades, the annual formation of winter sea ice no longer reliably extends to its usual reaches north of the South Shetland Islands. Instead, since the middle of the 1970s, this pack ice formed in that region only two years out of every six to eight years.

The pack ice contains a store of frozen diatoms, a critical food source for young crustaceans known as krill, which are the only food of Adelie penguins. Without pack ice in their spawning grounds, the entire generation of new krill dies and the only krill alive are those that survived from the last winter when there was pack ice.

Mr. Trivelpiece said the real problem was that ice had not formed in the krill spawning grounds for six winters now - about as long as most krill can live. He said that without a winter's ice soon, the last of the aging krill might never have the chance to reproduce before they expire threatening even healthy populations of Adelies now living at the bottom of the world.

"We're really out on the wire right now," he said. "If we don't get ice this winter or next, the whole house of cards will come down."

Copyright © 2001 The International Herald Tribune