Retreating ice behind population explosion in Adelie penguins?

Adelie penguins may be benefiting from shrinking glaciers, according to a new study that found the population of the species in East Antarctica has risen 135 times than it was around 19,000 years ago.
The study led by researchers at the University of Tasmania in Australia looked at the DNA of Adelie penguins to identify population trends over the last 22,000 years.
It found that the penguin population in East Antarctica is 135 times larger now than it was when the last ice age ended around 19,000 years ago.
Adelie penguins nest on ice-free land along the Antarctic coastline and therefore benefit from deglaciation, while their foraging for food for their chicks is made easier by a reduction in sea ice.

Lead author Jane Younger said the research showed that when considering the effects of climate change, it is important to consider the long-term impact over millennia as well as the immediate effects.
"We found that the Adelie penguin population in East Antarctica was very small during the ice age, but then penguin numbers increased by roughly 135-fold after the ice age ended," said Younger.

"The increase started around 14,000 years ago, about the same time as glaciers were shrinking in East Antarctica.
"Glacier retreat provided new ice-free ground suitable for Adelie penguin nesting (unlike emperor penguins, the Adelies cannot breed on ice)," she said.

However, Younger said the benefits for the East Antarctic Adelies could be balanced by the impact of climate change on its main food sources, and by less favourable conditions in other parts of the Antarctic.
"For Adelie penguin populations to expand they must have adequate food supplies to meet the requirements of the expanding population," said Younger.
"Whether this will be the case in the future remains to be seen, as the impacts of climate change on Adelie penguin prey species, such as Antarctic krill, are unclear at this time," she said.
"It is very important to note that Adelie penguin numbers are declining in some parts of Antarctica, it would therefore be incorrect to state that climate change is universally good for Adelie penguins," Younger added.

The study was published in the journal BMC Evolutionary Biology.