Web edition: February 14, 2009
Print edition: March 14, 2009; Vol.175 #6 (p. 18)
Most of the year, Dee Boersma works at the University of Washington. But for 26 years, she has made long visits to the southern Atlantic coast of Argentina to study Magellanic penguins. Her base is Punta Tombo. It’s home to the largest Patagonian penguin colony, some 200,000 breeding pairs. This population is relatively healthy, as penguins go. But then again, that isn’t saying much. Fourteen of the world’s 18 penguin species are in dire straits. The Magellanic penguins are just declining in numbers, Boersma says — and finding that “their cost of living is going up.”
And up. And up.
At the American Association for the Advancement of Science annual meeting, Friday, Boersma described data from the Punta Tombo colony and some of its environmental exiles — pioneering birds that have begun moving northward, up the coast to establish new settlements. All of these birds have been attempting to adapt to erratic and rapidly changing weather patterns.
“But they can’t move as fast as climate change is occurring,” Boersma said, so their prospects are anything but rosy.
She described a host of environmental assaults that have been relentlessly hammering the birds.
Around mid-century, foraging penguins regularly encountered spills of crude oil. For a while in late ‘80s and early 1990s, she would walk the beaches and find 60 to 90 percent of the dead birds she encountered coated with oil. Once coated with oil, penguins head for land where they can stay warm, she explains.
Every time they hit the water in search of food, they probably experienced a chill. Without food, they’d “eventually starve.”
When the government cracked down on illegal oil dumping, numbers of oil-soaked birds plummeted, Boersma found.
However, at about the same time, a more subtle threat emerged. Frequent swings in climate — from warm seasons to cold ones — affected where lunch was served. Magellanic penguins feed primarily on anchovy, hake and squid. Populations of these prey moved in response to climate.
Beginning in 1997, Boersma’s crew began strapping $3,000 satellite tracking devices onto the backs of some penguins to establish their foraging times and distances. And these showed that the distance from penguin nesting sites to feeding grounds during the egg-incubation period for the Punta Tombo colony varied dramatically from year to year. Mom’s or dad’s round-trip distance to the food court in 2004 was about 350 kilometers. The next year it was 450 km. And in 2002 it was a whopping 560 km.
While one parent goes out to eat, the other stays home on egg duty. And starves until its mate returns from a feeding frenzy. The longer a penguin is gone, the hungrier its mate will become. And it goes without saying that overly hungry penguins are not healthy birds.
One way the Punta Tombo colony has attempted to adapt has been to lay its eggs a little later — an average of three days later every decade, Boersma reported. However, this means that once the young hatch, they now have a shortened period to fatten up and fledge. And if, during this period, mom or dad spends too much time at sea looking for food, the chick may die of hunger before its carry-out meal arrives.
Another of this species’ trials: Rain.
Magellanic penguins live in a desert. For safety, they burrow into gravel. But should more than 60 millimeters of rain fall during a three-month period beginning in mid-October, their homes will become transformed into “swimming pools,” Boersma says. “And penguins do not like to live in swimming pools.”
Babies may drown. Even adults can succumb if torrential rains trap them in collapsed burrows. And in recent years, Boersma says, heavy rains have taken their toll.
The penguins have not taken all of these changes sitting down. As climate has become increasingly variable, the penguins have started emigrating. Because their food has been moving generally northward, the birds have begun establishing new subcolonies at more northerly coastal sites.
For instance, a single pair of Magellanic penguins appeared up the coast at San Lorenzo, for the first time, in the 1980s. “I did a big survey in San Lorenzo this year,” Boersma says, “and we estimate now that there are 90,000 breeding pairs.”
In 2000, 20 penguins staked claim to a homestead still further north, at Complejo Islote Lobos. In 2008, this settlement now hosted 200 breeding pairs.
In Punta Tombo and another well-established site, the Argentine government has set up reserves that protect the birds. But as penguins migrate northward, they’re moving into unprotected territory, Boersma observes, and may find conflicts with human settlements, fishing fleets — even tourists.
To Boersma, these birds are incredible sentinels of the marine world — and how humanity is altering it.
Boersma, D. 2009. Mare Nova: Climate Change — An Adaptive Challenge to Ocean Ecosystems. American Association for the Advancement of Science annual meeting (Feb. 13).
Boersma, D. 2008. Penguins as Marine Sentinels. BioScience 58(July/August):597.