Climate change is causing penguins a stressful commute.
Wed, Feb 18, 2009 at 06:10 PM
Imagine buying a house in Chicago's suburbs so you can commute to work in the city, and suddenly your job is moved to Des Moines. That's what's happening to the Magellanic penguins that live on the coast of Argentina, according to University of Washington biologist Dr. Dee Boersma. "For penguins, the cost of living is going up and they're having to work harder and harder to keep it going," says Boersma, who's studied penguins for 30 years and directs the Wildlife Conservation Society's Penguin Project. What's causing the penguins' debilitating long commute? Climate change.
Presenting her latest research at the American Association for the Advancement of Science annual meeting in Chicago last weekend, Boersma explained that shifting ocean conditions — changes in temperature and circulation — and overfishing are among the factors pushing penguins to travel farther and father to find food. "When they go out to forage, penguins are swimming about 25 miles farther than they did a decade ago," Boersma said. "While they're swimming, their mate is sitting on the nest starving and fasting, so they're both in this vicious cycle.
"When they're raising their chicks, Magellanic penguins are racing against their own physiology," she added. To find fish for their new chicks, the penguins now have to travel about 30 miles farther than they did a decade ago. The 60-mile round trip requires a lot of energy, which impacts both parent and chick.
As ocean temperatures and current patterns change, so do numbers and locations of different fish species, said Dr. William Cheung, lecturer in marine ecosystem services at the U.K.'s University of East Anglia, who also presented his work at the AAAS meeting. These changes are affecting anchovies, the favorite food of Magellanic penguins. Until recently, anchovies have been reliably abundant near the penguins' winter breeding grounds at Punta Tombo, Argentina. Now the fish are going farther and farther north.
These fish are now abundant, but Boersma is concerned that Argentina may begin to exploit its anchovies as Peru has. Overfishing there has led to the severe decline in local seabirds. Climate change impacts, said scientists at AAAS, make marine conservation more important than ever.
Climate change causes increased variations in ocean conditions — the temperatures and currents that determine food supplies and other factors that allow fish to thrive. To find both, the anchovies on which penguins depend are moving north. Penguins are having trouble adapting to this change. Last year, penguins followed anchovies as far north as Brazil, nearly to the equator. "Over a thousand died as a result," Boersma said.
"Over the past two decades, we've also seen that the penguins are laying their eggs three days later than they used to, so breeding season is getting shorter. Therefore the chances of chicks leaving the nest at a time when there is no food gets greater and greater," Boersma said. And if adult penguins aren't in good condition, they may not come back to their nesting grounds; some females have even begun to skip a breeding season, resulting in lower penguin numbers overall. "Over the last 22 years, these penguins have declined by over 20 percent. Of the world's 19 penguin species, 12 are in trouble," Boersma said.
Penguins are adapting to some extent, "voting with their feet," Boersma said. They're moving north to new winter breeding grounds, but this poses additional challenges to their survival. As they move north, closer to food sources, penguins are leaving protected reserves and settling on private lands. Outside conservation zones, they're vulnerable to direct human impacts. In addition, changing weather has increased heavy rains over the past 25 years, killing large numbers of penguin chicks.
"I think of penguins as ocean sentinels," Boersma said. "Penguins are already seeing the impacts of climate change and telling us there are problems. The difficulty is in being proactive.
"Fundamentally," she continued, "we have to control ourselves and our consumption. If we don't, we'll see more of these system breakdowns and both people and penguins will suffer."
For more on Boersma's research and the Penguin Project, see her page at the University of Washington website.