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News: Penguin populations falling steeply

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  • Robert Karl Stonjek
    Penguin populations falling steeply: biologist July 1, 2008 Courtesy University of Washington and World Science staff Like the proverbial canary in the coal
    Message 1 of 1 , Jul 1, 2008
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      Penguin populations falling steeply: biologist

      July 1, 2008
      Courtesy University of Washington
      and
      World Science staff

      Like the proverbial canary in the coal mine, penguins are sounding the alarm for potentially catastrophic changes in the world's oceans, a University of Washington biologist says.

      The culprits are global warming, oil pollution, depletion of fisheries and rampant coastline development, which threaten breeding habitats for many penguin species, she argues.

      These factors are behind rapid population declines among the birds, said the university's Dee Boersma, an authority on penguins. 

      "Penguins are among those species that show us that we are making fundamental changes to our world," she said. "The fate of all species is to go extinct, but there are some species that go extinct before their time and we are facing that possibility with some penguins."

      In a paper published in the July-August edition of the research journal BioScience, Boersma notes there are 16 to 19 penguin species, and most penguins are at 43 sites, virtually all in the Southern Hemisphere. 

      For most of these colonies, population trends have been unclear, so few people realized that many penguins were suffering sharp population declines, Boersma said. She advocates an international effort to check on the largest colonies of each penguin species at least every five years.

       

      Rain has soaked this Adélie penguin chick in Antarctica before its feathers are capable of repelling water. Though the icy continent is in essence a dessert, coastal rainfall is becoming more common with changing climate. (Courtesy Dee Boersma)




      Working with the Wildlife Conservation Society and colleagues, Boersma has studied the world's largest breeding colony of Magellanic penguins at Punta Tombo on Argentina's Atlantic coast. That population probably peaked at about 400,000 pairs between the late 1960s and early 1980s, and today is half that, she said.

      There are similar stories from other regions. African penguins decreased from 1.5 million pairs a century ago to just 63,000 pairs by 2005, Boersma claimed. Galapagos Islands penguins, the only species whose range extends into the Northern Hemisphere, now number around 2,500, about a quarter of what their population was when Boersma first studied them in the 1970s.

      Boersma recounts watching in 2006 as climate anomalies wreaked havoc on the same population of Emperor penguins featured in the popular 2005 film "March of the Penguins." The colony bred in the same place as in other years, where the ice is protected from the open sea and wind keeps snow from piling up and freezing the eggs. But in September, with the chicks just more than half-grown, the adults apparently sensed danger and uncharacteristically marched the colony more than three miles to different ice. 

      The ice they chose remained intact the longest, but in late September a strong storm broke it up and the chicks were forced into the water, Boersma said. While the adults could survive, the chicks needed two more months of feather growth and buildup of insulating fat to be independent. The likely result, Boersma said, was a total colonywide breeding failure that year.

      Global warming also appears to be key in the decline of Galapagos penguins, she said: as the atmosphere and ocean get warmer, El Niño Southern Oscillation events, which affect weather worldwide, seem to occur more often. During those times, ocean currents that carry the small fish that penguins eat are pushed farther away from the islands and the birds often starve or are left too weak to breed.

      These problems raise the question of whether humans are making it too hard for other species to coexist, Boersma argued. Penguins in places like Argentina, the Falklands and Africa run rising risks of being fouled by oil, either from ocean drilling or because of petroleum discharge from passing ships, she continued. The birds' chances of getting oiled are also rising because they often have to forage much farther than before to find prey.

      "As the fish humans have traditionally eaten get more and more scarce, we are fishing down the food chain and now we are beginning to compete more directly with smaller organisms for the food they depend on," she said. As the world's population continues to explode and more and more people live in coastal areas, the negative effects are growing for both marine and shore-based habitats used by a variety of species, Boersma added.

      "I don't think we can wait. In 1960 we had three billion people in the world. Now it's 6.7 billion and it's expected to be eight billion by 2025," she said. "We've waited a very long time. It's clear that humans have changed the face of the Earth and we have changed the face of the oceans, but we just can't see it. We've already waited too long."

      Source: WorldScience
      http://www.world-science.net/othernews/080701_penguins

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      Robert Karl Stonjek

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