The world's second largest colony of emperor penguins appears to have suffered an "unprecedented" breeding failure after penguins failed to raise any new chicks for the third year in a row at one of their biggest breeding grounds – not particularly chirpy news for World Penguin Day.
In a typical year, between 14,000 and 25,000 breeding pairs of emperor penguins – up to 9 percent of the global emperor penguin population – would make an annual migration to a breeding site at Halley Bay on the Brunt Ice Shelf in the Weddell Sea.
However, in October 2016, the northern side of the Brunt Ice Shelf suffered a series of cataclysmic breakups. Along with killing thousands of emperor penguin chicks, which were not yet at fledging age, the disruption also forced the mating pairs to seek out better breeding grounds.
A small amount of breeding might have occurred in Halley Bay in 2018, but 2016 and 2017 saw absolutely none whatsoever. The study notes that there’s been a “massive increase” in penguins breeding in the nearby Dawson-Lambton breeding area. Although that’s encouraging, the effect of the disruption at Halley Bay is still having a profound effect on the population as a whole.
Scientists from the British Antarctic Survey (BAS) have been keeping their eye on the Halley Bay colony using satellite imagery (image below). As reported in the journal Antarctic Science, their survey found that the colony has suffered three consecutive years of almost total breeding failure, something that they say is “unprecedented in the historical record.”
“We have been tracking the population of this, and other colonies in the region, for the last decade using very high-resolution satellite imagery. These images have clearly shown the catastrophic breeding failure at this site over the last three years,” Dr Peter Fretwell, lead author and BAS remote sensing specialist, said in a statement.
“Our specialized satellite image analysis can detect individuals and penguin huddles, so we can estimate the population based on the known density of the groups to give a reliable estimate of colony size.”
The researchers say the fall of the Brunt Ice Shelf cannot be directly attributed to climate change and most likely corresponds to an especially strong El Niño warm phase in 2015. However, they note that we can only expect to see more of this kind of catastrophe as sea-ice loss continues to increase with rising global temperatures.
“It is impossible to say whether the changes in sea-ice conditions at Halley Bay are specifically related to climate change, but such a complete failure to breed successfully is unprecedented at this site,” added Dr Phil Trathan, study co-author and BAS penguin expert.
“Even taking into account levels of ecological uncertainty, published models suggest that emperor penguin numbers are set to fall dramatically, losing 50-70 percent of their numbers before the end of this century as sea-ice conditions change as a result of climate change.”