The Rise and Fall of Penguin Populations

Over the last 30,000 years, a new study says, penguin populations have risen and fallen. Between the last Ice Age and up to around 1,000 years ago, penguins actually benefitted from the warming climates and retreating ice - though polar bears might disagree - suggesting that recently observed declines in penguin populations are the result of ice retreating too far and too fast.

As detailed in the paper published in the journal Scientific Reports, an international team of scientists used a genetic technique to determine at what point penguin populations diversified in order to recreate population sizes.

About 30,000 years before humans become more industrialized and added another element to climate change, and Antarctica was warming, three species of penguin - Chinstrap, Adélie and southern populations of Gentoo penguins - increased in numbers.

Though normally you might expect an opposite effect, this research exemplifies the adage "too much of a good thing."

"Whereas we typically think of penguins as relying on ice, this research shows that during the last ice age there was probably too much ice around Antarctica to support the large populations we see today," lead author Gemma Clucas, from Ocean and Earth Sciences at the University of Southampton, said in a statement. "The penguins we studied need ice-free ground to breed on and they need to be able to access the ocean to feed. The extensive ice-sheets and sea ice around Antarctica would have made it inhospitable for them."

Researchers collected feathers and blood samples from 537 penguins in colonies around the Antarctic Peninsula. After sequencing a region of mitochondrial DNA that evolves relatively quickly, they found that penguin populaces varied depending on the climate.

"What we have found is that over the last 30,000 years different penguin species have responded very differently to a gradually warming world, not something we might expect given the damage current rapid warming seems to be doing to penguins' prospects."

Scientists stress the fact that their findings do not mean climate change is necessarily good for these flightless birds. Currently, with the exception of the Gentoo penguin, populations of the other two penguins are dropping, most likely because as more ice melts away, so does the krill stock they depend on for food.

As fellow researcher Gemma Clucas puts it, "climate change today is creating lots of losers and few winners."