Australian and New Zealand scientists have recorded a 90% decline in the numbers breeding at Cape Dennison in Commonwealth Bay.
Writing in the journal Antarctic Science, they warn that the colony could disappear completely within 20 years unless the berg disintegrates or moves on. The demise, they say, has ‘important implications for wider east Antarctica if the current increasing sea-ice trend continues’.
The bay used to be free of sea-ice, making it an ideal place for penguins to nest. Then, in December 2010, disaster struck. A giant iceberg, which had calved 15 years previously, ran aground in the bay and has remained stuck there ever since. Ice would normally be swept out to sea but now the 3,000km2 berg blocks the flow, leading to a build-up 3m thick. Adélie penguins need bare land with small stones to build their nests. They must also have ready access to the sea. Open water used to be within 3km of their colony but now the birds must waddle 60km, each way, to find food. Exhausted adults and chicks, heading for the sea, collapse en route and die.
Thanks to Jules Dumont d’Urville, we can admire the Venus de Milo in the Louvre. This polymath naval officer persuaded France’s ambassador to Turkey to buy the fragmented statue. Explorers, such as Shackleton and Tom Creen, were ‘hard men’ but D’Urville had a softer side. In 1822, during a scientific mission to the South Seas, he discovered a ‘new’ species of penguin. Homesick and pining for his wife, Adélie, back in France, he named the bird after her. A slice of Antarctica, stretching from the east coast of the continent to the South Pole and claimed by him for France in 1840, is still known as Adélie Land.
D’Urville’s mother considered Adélie, the daughter of a clockmaker, unworthy of her son and refused to meet her or the grandchildren. Did the lovesick adventurer immortalise his wife’s name to spite his snobbish mother?
The medium-sized penguin, clad in evening dress and with a white ring around the eye, is one of the most southerly breeding birds in the world. “They are extraordinarily like children, these little people of the Antarctic, or like old men, full of their own importance” wrote Cherry-Garrard in The Worst Journey in the World, his memoir of Robert Falcon Scott’s tragic polar expedition. Four million pairs of Adélies breed at 250 sites in Antarctica. Colonies can have hundreds of thousands of nests.
During the 1970s, scientists noticed that penguin numbers were declining in the Antarctic Peninsula, the spur of land jutting from the frozen continent towards South America. Sea temperatures there were rising. The poles are warming much more rapidly than other parts of the world. Adélies, especially vulnerable to climate change, face an uncertain future.
According to some newspaper reports, blockage by the iceberg, ‘the size of Rome’, has killed the missing penguins of Cape Dennison. Only 10,000 are said to have survived. Not all experts agree, however.
When a similar incident occurred in the Ross Sea in 2001, the birds simply moved to another location. CBS News quotes Michelle La Rue, a penguin expert from the University of Minnesota; “Just because there are a lot fewer birds observed doesn’t automatically mean that the ones that were there before have perished.
“They easily could have moved elsewhere, which would make sense if nearby colonies are thriving,” she said. Corpses of adults and chicks lie strewn along the route to the sea but there aren’t 150,000 of them. Nothing decomposes in the world’s great southern freezer; penguin colonies can have carcasses scattered about for years.
- Jayne Wilson et al. The impact of the giant iceberg B09B on population size and breeding success of Adélie penguins in Commonwealth Bay, Antarctica. Antarctic Science. 2016