WASHINGTON, January 31, 2014 — More frequent rainstorms and high temperatures resulting from climate change are killing large numbers of Magellanic penguin chicks, according to a study published Wednesday in the journal PLOS ONE.
Authored by conservation biologist Dee Boersma and biologist Ginger A. Rebstock, the study is the first to demonstrate how climate change directly impacts sea birds. It is the result of data compiled over 28 years from the penguins in Punta Tombo, Argentina, as well as recordings of regional temperatures and precipitation.
Punta Tombo, located midway along Argentina’s coast, has the largest Magellanic penguin colony in the world, with about 200,000 breeding pairs. While relatively small — about 15 inches in height as adults — Magellanic penguins are known for their loud brays, screeches and honks.
Dr. Boersma says that penguin populations are dropping below original populations by as much as 20 to 24 percent, but scientists are unsure why. However, according to the study, climate change may be a piece of the puzzle.
In Punta Tombo since 1982, with support from the Wildlife Conservation Society, Dr. Boersma and a team of researchers have kept painstaking records and data on almost 3,500 chicks. The chicks were tracked from the moment they hatched to the time they left the nest, with scientists visiting their nests once and twice every day for the length of the six-month hatching period.
“We knew when each chick hatched, and its fate,” says Dr. Boersma.
In general only one third of the hatchlings survived to make it out of the nest. Not surprisingly, predation and starvation were found to be among the major contributing factors to the chicks’ deaths. However, Dr. Boersma also found that an increase in storms and heat were additionally major causes of chick mortality in Punta Tombo from 1983 to 2010.
While starvation and predation were more consistent, happening every year, storms and heat occurred during seasons with heavy storms or unseasonably high temperatures, both of which increased as the study progressed.
“In 1999 rain killed as many chicks as all other causes of death combined and in 1991 rain killed as many chicks as starvation and predation combined,” wrote Dr. Boersma.
Even though penguins are aquatic birds, they are not born that way. Instead of waterproof feathers, a penguin chick is born with a light down covering that makes the chick susceptible to hypothermia should it get wet. For this reason, penguins breed in arid or semi-arid coastlines with very little rainfall.
“Heavy rainfall was infrequent historically in arid areas, and seabird species have not had time to adapt to increasing storm frequency and intensity in the 20th century,” write the study authors.
In Punta Tombo, both the frequency and severity of storms, as well as unseasonably high heat, increased between 1960 and 2000, according to meteorological data and data collected by the researchers.
The study found that chicks were most vulnerable to storms when they were between nine and 23 days old because they were too large to be completely sheltered by their parents’ bodies, but too young to have waterproof plumage.
Another result of climate change, unseasonably high heat also killed chicks, albeit not as many as storms did. Extreme heat kills penguins, both chicks and adults, by making it difficult and ultimately impossible to regulate body temperature. Periods of unseasonably high heat are predicted to increase in the future and so are penguin deaths due to heat exposure.
Even though the study only analyzed Magellanic penguin chick deaths in Punta Tombo, they deduce that the same may be happening for several species of sea birds.
“Penguins are really the ocean’s sentinels,” said Dr. Boersma to the Christian Science Monitor. “They are telling us that we’d better start paying attention to climate change because penguins are dying from heat and these increased storms. At the same time we’re starting to see increased numbers of people die from these same sorts of things. So these penguins are really the canary in the coal mine.”