A mother Magellanic penguin pants doglike in the afternoon heat, shading her newborn chick from the hot sun. But it’s not enough. The chick’s thick downy coat isn’t designed for the heat, and its efforts to stretch out its wings and neck to cool off don’t work. Despite the mother’s best efforts, the youngster dies.
This sad story is becoming all too common among Magellanic penguins (Spheniscus magellanicus), according to a 27-year study published today. Researchers have found that the species, which has lost 20% of its population globally since 1987, faces a growing threat from increasing numbers of torrential rainstorms and sweltering heat waves caused by climate change, which could accelerate the species’ decline.
Named after Ferdinand Magellan, who spotted the birds in 1520, Magellanic penguins nest in burrows and under bushes in coastal Argentina, Chile, and the Falkland Islands. Like many other penguin species, the birds prefer temperate, dry climates. However, recently the climate has started to shift. Also, climate models predict the number of storms during the first 2 weeks of December, when chicks are most vulnerable, will roughly double by 2081. Newborn penguins are born with a fluffy down coat of feathers, but this layer isn't waterproof. Despite the best efforts of their parents, many storm-soaked chicks catch hypothermia and die. The same lack of waterproofing leads chicks to die from heat stroke on hot days, when a dip in the ocean is the best way to cool down but requires a waterproof coat. Climatologists predict air temperatures in the region will rise 2°C over the next century.
In 1982, a Japanese company sought the rights to harvest Magellanic penguins from a colony in Argentina. After Argentinians protested, the government drafted ecologist Dee Boersma from the University of Washington, Seattle, to survey the world’s largest Magellanic penguin colony, located in Punta Tombo, Argentina. Even after the Japanese company silently withdrew their plans, Boersma continued her study. For the next 27 years, she tracked the population’s ups and downs during the birds’ September to February nesting season. Up to twice a day, Boersma and her colleagues strolled through the nesting grounds monitoring newborn chicks. When a chick turned up dead or went missing, they tallied the loss and investigated the cause.
In an average year, Boersma and her fellow researchers discovered that 65% of all chicks died, with most from starvation, predation, and disease. However, the team discovered the changing climate has taken its toll. Over the course of the study, the number of storms during the nesting season increased. In the most recent 3 years, an average of 7% of chicks died from chilling rainstorms and heat exhaustion, but during some years the number was much higher, the researchers report today in PLOS ONE. In 1999, a single storm killed 40% of all chicks, the same as all other causes of death that year combined, Boersma says. Calculating an overall trend in climate-related deaths is difficult due to the irregularity of severe storms, Boersma says, though the link between extreme weather and chick death demonstrates that as extreme weather increases in coming years, chick death will increase in turn. In addition, the penguins now tend to arrive at the breeding site later in the year, likely because the fish they eat are arriving later due to changing ocean temperatures. Chicks hatched later in the season are too young to survive the November and December feather-soaking storms, which Boersma thinks compounds the problem.
“This is not something that penguins can evolutionarily adapt to—it’s too quick and these events are too extreme,” Boersma says. “The weather has become a very important mortality factor and it didn’t used to be.”
Pablo García Borboroglu, president of the Global Penguin Society and an ecologist for the National Research Council of Argentina, says although the recent weather-related deaths are a growing factor in chick death, they’re still not the biggest concern. “The lack of food for the species is still the key thing,” he says. “Even if the recent climate change is human-caused, climate change can’t be addressed in the short term. The lack of food is something we as human beings can immediately address.”
Borboroglu and the Global Penguin Society are working with the Argentinian government to create a marine sanctuary for Magellanic penguins, an effort Borboroglu hopes will help increase the penguins’ food supply and reduce chick deaths.